Ensign Wasp Facts: Nature’s Cockroach Eliminators

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Want to learn about a natural solution to finishing off roaches in your neighborhood? Learn all about Ensign Wasps in the article below.

Cockroaches are one of the most troublesome pests in the house.

They look creepy and gross, plus they cause several diseases like Typhoid Fever, Cholera, and more.

While insecticides are effective against these pests, they can harm you and your family if used carelessly.

Pests Destroying Your Garden? Learn the secrets to eliminating pests in your yard or garden in the most earth friendly way possible.

Ensign wasps are one of the best natural controllers of cockroach populations.

But what are they, and how do they eradicate cockroaches?

Let us find out in the article.

Ensign Wasp Carnage

What Are Ensign Wasps?

Ensign wasps are tiny insects that belong to the Evaniida family and are also commonly known as hatchet wasps.

Due to the way their abdomens move up and down, creating a flag-like illusion, they were given the name “Ensign wasps”.

They are classified as parasitoids due to the way their larvae feed on cockroach eggs.

Unlike social wasps, these insects do not live in colonies; They are solitary wasps that do not build hives or nests.

There are around 400 different species of Ensign wasps scattered throughout the world.

Let us take a look at the physical features of this fascinating little insect.

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What Do Ensign Wasps Look Like?

Ensign wasps look similar to flies. But if you look closely, there are many notable differences. The body is black, but the abdomen looks like a triangular flag.

The male ensign wasps have oval-shaped abdomens, while the female ensign wasps have triangular abdomens.

These black wasps have a 0.1 to 0.2 inches long body. The wings are mostly clear and transparent.

Ensign Wasp

Types of Ensign Wasps

There are many different types of ensign wasps found across the globe.

The blue-eyed ensign wasp is one the largest species of ensign wasp.

As the name suggests, these wasps are known for their blue-colored eyes. They are also called the common cockroach egg parasitoid wasp.

Apart from their blue eyes, these insects can be identified by wide separation in the leg segments that attaches to the body of the wasp.

The other large one is the brown-marked Prosevania Fuscipes. These are not found in the Australian and Antarctic regions.

What Does A Ensign Wasp Eat?

We mentioned at the beginning that Ensign wasps can eliminate cockroach populations. You might have assumed that they eat cockroaches, but that’s not how it works.

They do not hunt and consume adult cockroaches; these insects are experts in taking down cockroach eggs.

The Ensign wasp larva depends on cockroach eggs to survive and grow. A tiny ensign wasp larva can eat out an entire batch of cockroach eggs.

Adult wasps, on the other hand, rely on nectar to fulfill their diets. You can often spot them flying around blooming gardens in search of nectar.

At times, they also consume the honeydew on leaves left by various aphids.

The availability of food is a significant factor in determining where the mother wasp will lay their eggs.

Ensign Wasp

Where Do Ensign Wasps Live?

Various species of ensign wasps are scattered around the globe. The only places where you cannot find them are the polar regions.

In the US, Ensign wasps are commonly found in the southern states. You can also spot them in the far north regions like New York City.

These wasps like to be around areas with a significant cockroach population (which makes New York perfect for them!)

If you find these insects around your house or yard, let them be.

These tiny experts will wipe down the cockroach population in a short time.

Be it the American cockroach eggs or the oriental cockroach eggs, ensign wasps will take care of them.

Amazing right?

If you want these insects around your home, have a nice garden with bright flowers. Adult wasps rely on nectar to complete their diets.

Life Cycle of An Ensign Wasp

Being a parasitoid wasp, the female does not build a nest to lay eggs. After mating, the mother wasp searches for areas with rich cockroach populations.

These insects undergo the 4 stages of metamorphosis – eggs, larvae, pupae, and adults. Let’s understand all of this.

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Laying Eggs

To start off, ensign wasps are cockroach oothecal parasitoids. These insects track down spots where cockroaches have laid eggs.

They then carefully drop their egg in the cluster of cockroach oothecae eggs.

Some females oviposit the eggs when the female cockroaches carry a fresh batch of eggs in their bodies.

Ensign Wasp


The ensign wasp larva hatches before the cockroaches and starts consuming the eggs to get the necessary nutrients for growth.

You will be surprised to know that this wasp can determine if a cockroach egg batch is already containing an ensign wasp egg.

The females refrain from dropping eggs in such situations as the wasp larvae can be cannibalistic.

This means whichever wasp egg hatches first will end up consuming all the other eggs in the batch, including the second ensign wasp egg.


After emerging the larvae molt five times.

By the end of this stage, they entirely finish eating the eggs within the case and then pupate.


Once fully grown, they escape the case through a small hole and start consuming nectar and honeydew left by aphids to fulfill the nutrition requirements.

Mating Rituals of Ensign Wasps

There is not a lot of data about the mating rituals of ensign wasps, but there are a few fascinating points to note from their reproduction pattern.

The female ensign wasp tracks a cockroach egg case and they begin to vibrate its antennae over the case while keeping the body lined parallel with the long axis.

She continues this process for around 15-30 minutes. After completing this process she inserts the egg into the cockroach egg cluster.

How Long Do Ensign Wasps Live?

As adults, ensign wasps do not live for long. An average adult usually lives for 2-3 weeks.

In the wild, they can be hunted down by predators like birds.

Humans also often end up killing them as they look like annoying flies.

Some even consider them dangerous. But are they a threat to humans? Let us explore this in the next section.

Ensign Wasp

Do They Bite?

Due to their tiny waist, they might look a little like thread-waisted wasps, but these insects do not bite or sting.

Ensign wasps are not aggressive, and there is no need to kill them.

These wasps will quietly eliminate cockroach eggs and drink nectar from nearby flowers.

Are They Poisonous/Venomous?

Ensign wasps are not poisonous/venomous. They might look a little intimidating due to their jet-black body, but they cause no harm.

Plus adults die within 2-3 weeks, so there is no need to take any drastic measures to kill them.

Are They Harmful or Beneficial to Humans?

As mentioned above, ensign wasps do not harm humans. These insects are beneficial as they help cockroach populations by eliminating eggs.

This means you do not have to spend money on various treatments of oothecae to remove them.

Yes, they consume nectar and honeydew left by aphids on leaves, but like species of gall wasp, they do not damage the appearance of the plant by leaving galls on the leaves.

What Are Ensign Wasps Attracted To?

Ensign wasps emerge from an area with abundant cockroach populations. The female selects spots where they can find plenty of cockroach egg clusters.

The adult is also fond of nectar; therefore, you can find them around flowers and plants like parsley and fennel. They also love honeydew left by aphids.

How To Get Rid of Ensign Wasps?

Ensign wasps are not the bad guys in your home. These insects will actually help you eliminate the real bad guys- cockroaches.

However, you must know that these insects cannot straight-away eradicate cockroach populations from an area.

You can use a broom or fly swatter to kill these insects. Keeping cockroach populations in check will also help to reduce ensign wasp visits.

Using pesticides inside your home is not ideal, as they can harm you and your family.

If you find the wasps near your house, let them be. In a few days, they will die.

Plus, they will also take down the cockroach population to some extent. If the cockroach populations go out of control, seek professional help.

Interesting Facts About Ensign Wasps

This article is filled with information about ensign wasps. However, there can be a few fascinating things that you might have missed about these insects. Let us take a look at them:

  1. Ensign wasps are one of the most efficient parasitoids of cockroaches. These insects can eliminate at least 3 different types of cockroaches, including the troublesome American cockroach.
  2. At times female ensign wasps oviposit the cockroach eggs while they are carried around by the mother cockroach.
  3. Ensign wasp larvae can be cannibalistic, which is why females restrain from laying the egg in a cockroach egg cluster that already has an ensign wasp egg.
  4. Ensign wasps are found in every corner of the world except the polar regions.

Frequently Asked Questions

Does ensign wasp bite?

Ensign wasps do not bite or sting and are not aggressive. They eliminate cockroach eggs and drink nectar from nearby flowers.
They are not poisonous/venomous and do not harm humans.
They are beneficial as they help eliminate cockroach populations and do not damage the appearance of plants.
Adults live for only 2-3 weeks, so there is no need to kill them.

What to do with ensign wasps?

There is no need to do anything about ensign wasps. They are neither stinging insects, nor are they poisonous or venomous in any way.
You don’t need to be worried about the wasps at all.
On the other hand, having Ensign wasps around often means that there are cockroach eggs or adult roaches in your home.
You should search for signs of roaches and take action to prevent their infestation if you find ensign wasps in your home.
The wasps themselves can also help with removing the roaches.

What is the world’s worst wasp?

We assume this means the worst stinging wasps. 
The tarantula hawk has a sting that is rated at the top of the pain scale, but it is not the most painful insect in the world – that crown goes to bullet ants.
The sting is described as blinding, fierce, and shockingly electric.
Tarantula hawks are not aggressive towards humans but they paralyze tarantulas and lay eggs on them, with the larvae feeding on the spider.
They are primarily found in desert regions and have bright wings that act as a warning to predators.

What is the most peaceful wasp?

Wasps are mostly peaceful. It is a myth that wasps are aggressive and are out to sting you.
They will not bite or sting you unless they see you as some kind of danger.
In general, solitary wasps are more peaceful than social ones.
This is because they don’t have a nesting colony to protect. But even they can get aggressive if you try to destroy their nest.
There are several types of wasps that are solitary. Most notably, the entire class of thread-waisted wasps is like this.
Giant ichneumons are also solitary parasitoid wasps.

Wrap Up

Ensign wasps may look like flies but are an excellent source to eliminate cockroaches. 

These parasitoid wasps lay an egg in every cockroach egg cluster, and the wasp larva consumes the cockroach eggs.

The black body and blue eyes might look intimidating, but they are entirely harmless. They do not sting or bite and are non-poisonous.

If you find them near your house, do not kill them; they will help you get rid of the nasty cockroaches.

Thank you for reading the article!

Reader Emails

Ensign wasps are scary to look at, but that’s all there is to it. They are of no danger to humans, they can’t even sting you to protect themselves.

But their appearance often causes a lot of fear, and the scores of letters we receive every year about these wasps is testimony to that.

Please go through some of the emails from our readers about these wasps.

Letter 1 – Ensign Wasp


What fly or wasp is this
I live in Miami, Florida and I am constantly finding this insect flying around in my kitchen. Never more than 1 at a time.

Hi Brian,
This is an Ensign Wasp, a species that parasizes the eggs of Cockroaches.

Letter 2 – Ensign Wasp


housefly with long cricket legs
Sun, Jun 28, 2009 at 7:54 PM
This was flying all around my apartment in San Antonio, TX the other night and swooped in on me once. I was concerned because it had long dangling legs like a wasp. It was probably at least 90 degrees or warmer out. I don’t recall it making any noise but it was flying in kind of a slow hover pattern. Eventually it flew into a fan and alas it was no more. Looks like a cross between a housefly and cricket. Is it a juvenile cricket? Thanks.
San Antonio,TX 78212

Ensign Wasp
Ensign Wasp

Hi Kate,
You will probably lament this Ensign Wasp’s untimely demise after learning that Ensign Wasps in the family Evaniidae parasitize the egg capsules of Cockroaches.

Letter 3 – Ensign Wasp escapes becoming Unnecessary Carnage


August 11, 2009
This bug started to appear a few weeks ago, I found the first one on the living room and quickly squashed it. A couple of days later there was another one and killed it too. About a week later AGAIN the same bug (maybe) came back, I even started to think that it was the exactly the same bug I killed before.
Yesterday I killed this bug again and left it in the living room with a Pringles cap on top of it, the insect was moving and it was trapped.
A few minutes later I checked it again and it was gone, it disappeared as my son claims.
I found it again flying like nothing, I believe this bug can seriously take a beating.
I took this picture with a zoom lens because the ceiling is about 20 feet high.
So if you can help me identify this, I dont know if it is dangerous or not, I have killed one with my bare hands.
P.S. Please don’t make my email public.
Father of Two
McAllen, TEXAS

Ensign Wasp
Ensign Wasp

Dear Father of Two,
You do not want to kill Ensign Wasps.  They will not sting you and they are beneficial since they parasitize the eggs of cockroaches.  Allowing the Ensign Wasps to live will reduce the Cockroaches in your area.  Though the wasp in your image is alive, we want to tag your letter as Unnecessary Carnage because it nearly met with a squashing end like its predecessors.  We do not publicize email addresses, but submitting a letter to our website is done with the understanding that we post content to our site.

Letter 4 – Ensign Wasp squashed out of fear


Black wasp with blue eyes
September 5, 2009
I found this black wasp in our chihuahua’s bed after it had apparently bitten or stung her. It was inside the house and seemed to prefer to crawl rather than fly as I had to chase it out of the bed to catch it. My initial instinct was to grab a paper towel and squish it since I did not want to be stung. My second reaction was to grab the camera. Luckily, it seems to be quite tough and only the abdomen was injured. From tip to tail, it is a little less than one half inch long. It has very tiny wings, about 3/16th of an inch long. I can not tell if it does or doesn’t have a stinger. It has striking deep blue eyes.
Baton Rouge, Louisiana, USA

Ensign Wasp:  Unnecessary Carnage
Ensign Wasp: Unnecessary Carnage

Dear Tyson,
This is an Ensign Wasp, probably Evania appendigaster.  There is a photo on BugGuide that shows the same blue eyes.  Since Ensign Wasps parasitize the egg capsules of cockroaches, they are quite effective in the control of what many people would agree is one of the more undesirable household intruders.  We are nearly certain that Ensign Wasps are incapable of stinging.  If one does a bit of math, the single Ensign Wasp that you killed might have prevented hundreds of cockroaches from infesting your house by destroying eggs.  This single Ensign Wasp might then have prevented hundreds times hundreds (or tens of thousands) of Cockroaches in the second generation had the first generation all lived.  Would you like us to do the math for the third generation of Cockroaches that would have been prevented from existing?  Because of fear, all too often people have the inclination to kill and ask questions later, be that regarding the Unnecessary Carnage of arthropods or the irrational invasion of foreign countries.  We hope the next time an Ensign Wasp finds its way into your home, which it most likely did because of the available food source for its progeny, you will allow it to search for prey without intervention.

Letter 5 – Ensign Wasp


Ant Looking Fly
Location:  Houston, TX
July 30, 2010 3:13 pm
I caught this fly in my house. I’ve noticed a couple within the last week. Can you identify the fly? The ’odd’ behavior is the antenna’s and abdomen are constantly moving
Location: Houston, TX; Season: summer
Curious George

Ensign Wasp

Dear Curious George,
This Ensign Wasp gets its name from the way it carries its abdomen aloft and waves it about.  Ensign Wasps are parasitic on the ootheca or egg cases of Cockroaches.  We have been getting regular requests to identify Ensign Wasps so it appears their numbers are increasing, which is bad news for cockroaches.

Letter 6 – Ensign Wasp


Axe shaped rear end
Location:  Fort Worth, TX
September 30, 2010 6:59 pm
I have seen quite a few of these in and outside the house. Have no idea what it may be but the rear end tends to swing/chop up and down when it is landed, just like an axe swing. The wings are fly-like, clear and are the length of the body. The head and antennae look like an ant. The six legs are similiar to a cricket or such. Long thicker back legs with the other four like a fly or such.
Body aprox 3/8 inch; 3/4 inch overall length from head to extended legs.
Signature:  Thanks, David

Ensign Wasp

Hi David,
The Ensign Wasp gets its common name because of its habit of bobbing its abdomen up and down while hunting.  They are also known as Hatchet Wasps or Flag Wasps according to the Australian Museum website.  Ensign Wasps are a beneficial species and their presence should be encouraged because they parasitize the ootheca or egg cases of Cockroaches.

Thank you!  I have looked and looked until my eyes are bleary to try and match the bug to something on the web, but to no avail.
I thank you again!
David Bryan

Letter 7 – Ensign Wasp from Australia


What’s this bug??
Location: Sydney, Australia
February 20, 2011 1:21 am
Hi bugman,
We had two of these bug’s in the house today. We live in Sydney, Australia, it’s Summer and it’s a humid day around 30 degrees. What is it?
Signature: Sophie

Ensign Wasp

Hi Sophie,
This is a beneficial Ensign Wasp.  The female parasitizes the ootheca or egg case of cockroaches helping to keep the cockroach population in check.

Thanks for getting back to me so quickly and thank you for the answer. That makes sense – we have a huge cockroach population inside our house at the moment, it’s out of control.

Letter 8 – Ensign Wasp


Wasp, fly, cricket combo
Location: Houston ,TX
February 18, 2011 3:35 pm
Every spring and summer these little buggers end up in our bathrooms. This has happened in every house we have lived in and I cannot figure out what they are or how they get in. They sting and usually only come in one at a time, but we get a new one every few days for months on end.
Signature: Kelly Peyton

Ensign Wasp

I just found out what it is after searching “Houston” on your site…It’s an ensign wasp and I guess although they look like they sting they don’t? They sure have a BIG stinger!

Hi Kelly,
We are happy to hear you identified your Ensign Wasp using our archives.  We are surprised that you are reporting that they sting.  We believe the stinger is actually an ovipositor but in some insects, the ovipositor also serves as a stinger.  We hope you still consider the Ensign Wasp to be beneficial since the female parasitizes the ootheca or egg case of Cockroaches.

Letter 9 – Ensign Wasps suffocated and swatted


What is this pest???
Location:  Houston, Texas
July 12, 2011 8:46 PM
I found these two pests flying around my home yesterday and tonight July 11, 2011.  I recently moved into my new home and I now have a new pest to deal with.  This bug has hind legs similar to a grasshopper; wings like a fly; a bulb bottom like a wasp stinger; blue eyes; and is extremely hard to kill!  I placed the first one in this baggy and it lived for an entire day.  The second bug is still alive after I smashed it with a fly swatter and its been inside a closed bag for ten hours.  What is this scary looking mutant?
Lola @ Houston, Tx.
Teachers Make All Other Professions Possible!

Ensign Wasp Carnage

Dear Lola,
We find your letter most troubling and we hope we can use our response to educate you.  Our first challenge to you is to question why you automatically assumed that these Ensign Wasps are pests?  How do you define a pest?  We propose this to you because Ensign Wasps are harmless creatures that cannot sting humans.   Ensign Wasps parasitize the oothecae or egg cases of Cockroaches.  The wasp larva consumes the cockroach eggs before pupating within the now empty ootheca, helping to naturally control the population of cockroaches.  Without a natural means of control, Cockroaches will multiply and that might necessitate frequent visits from the exterminator which costs money and introduces poisonous pesticides to the home.  If there are Ensign Wasps in your home, that is probably an indication that a food supply is nearby.  We noticed your tagline that “Teachers Make All Other Professions Possible!” and we applaud you for using the internet to identify the creatures you have encountered in your home, but we wish that you had decided to educate yourself about them first before swatting and suffocating these beneficial creatures.  Not everything you encounter in your new home is a pest.

First and foremost, thank you very kindly for your quick response to my inquiry.  I am happy to finally put an identity to this new insect I have never before encountered.
Now, as far as my naming this wasp a “pest”, I find it completely fitting and I can briefly explain why (as you ask for my definition).  My four year old son became fearful of these wasps as they seem to purposely fly near our faces and around us and are not just spending time on a wall or in and out an open door or window.
Yes, as my tag mentions, I am a teacher and find it interesting that you mention it as some sort of way to belittle my wanting to rid this home of an insect I am unfamiliar with.  Though I do have great scientific interests, I find my son’s peace much more priority and anything disturbing him that I encounter will become secondary.  You mention I should have “educated” myself beforehand and I ask you, how else would I have been able to capture the photos, get a closer look, and educate myself had I not swatted these FAST flying wasps and placed it in a bag?
Truly you may want to consider proofreading your outgoing mail before hitting send and turning a newly interested reader to your site into someone who finds this more personally based than that of sharing knowledge.
Thanks again as I now have learned more than the name of this new insect.
Next time someone encounters your site and is genuinely seeking assistance in identifying an insect they’ve never before encountered don’t make it personal.  It takes away from your own credibility, as well as your site.
Thanks for this one time exchange.
Teachers Make All Other Professions Possible!

Letter 10 – Ensign Wasp and Carpenter Bee on Curacao


need help identifying Bug and Bee
Location: Island of Curaçao in the Caribbean
August 19, 2011 7:08 pm
Hi, I am Garrick Marchena, from the island of Curaçao in the Caribbean and I need help identifying these two insects.
I know one of them is a bee, but i need to know what type of bee. Its certainly a type I’ve never seen or heard of before.
The other is an insect known to our island as one that brings luck. It is called ”Mamoendenge” by our local people, but i need to know the official name. It kinda looks like a Mud Dobber wasp but i don’t think it is. Its back part bobs up and down as it walks.
I really appreciate if you can help, but if you can’t maybe you might know someone who does?
thanks you very much,
Garrick Marchena.
Signature: Garrick

Carpenter Bee: Xylocopa muscaria

Hi Garrick,
Though we don’t recognize your bee, and we have been unable to locate a match online, we suspect it is some species of Carpenter Bee.  The other insect which you call Mameondenge we find very interesting because of the notion that it brings bad luck.  This is a beneficial Ensign Wasp, so named because of the bobbing of its abdomen which is thought to resemble a flag.  The Ensign Wasp parasitizes the ootheca or egg cases of Cockroaches, helping to reduce their population.  We wonder if the name the locals have given it is a reference to dengue fever which is spread by mosquitoes.  You might want to educate the locals as to the importance the Ensign Wasp plays in Cockroach control.

Ensign Wasp

Thanks for the fast response!!!
Locals say that the Esign Wasp (or Mamonedenge) brings GOOD luck actually! Sorri i wasn’t clear on that.
Now that i know this information I’m gonna love this bug even more!
From what I’ve searched on the internet the bee does look like a carpenters bee. Also seems to be a type of solitary type bee.
This is really awesome!
Let me know if you are going to use the pictures because i would like to add a copyright on them first if you don’t mind.
Thank you very much for your help.

Sorry Garrick,
We somehow inserted the word “bad” before luck in your letter.  The images are already posted live and we have cropped them, lightened them and formatted them to our site.  Your name is printed with your original email.

Correction courtesy of John Ascher
April 22, 2012
Xylocopa (Schonnherria) muscaria (Fabricius, 1775) female:

Letter 11 – Ensign Wasp


Subject: HELP
Location: San Angelo, Texas
May 26, 2013 3:05 pm
I found several bugs in my apartment that have a body of an ant with fly wings and back legs like a cricket. What is it? Do they bite?
Signature: Thanks

Ensign Wasp
Ensign Wasp

This is a beneficial Ensign Wasp.  The female lays her eggs in the ootheca or egg case of cockroaches and the larval wasps feed on the developing cockroach eggs, helping to control the populations of the household pests.  We have postdated your submission to go live during our absence from the office in early June.

Letter 12 – Ensign Wasp


Subject: black long legs big head beetle?
Location: Miami Florida
November 14, 2013 9:26 pm
Dear whats that bug,
I just found this visitor in our bathroom in the morning in November in Miami Florida.
Is not as beautiful as other bugs that i see in this website but I am just move by curiosity.
I could not found any picture online exactly as this guy . I think is a beetle
I took the pic with my cell phone and the animal was very high in the wall so i couldn’t get closer.
Thank you in advance
Signature: vlad

Ensign Wasp
Ensign Wasp

Dear Vlad,
This is an Ensign Wasp, and you should probably welcome it into your home.  The female Ensign Wasp parasitizes the ootheca or egg case of a Cockroach, and the developing Ensign Wasp larva feeds upon the eggs and developing Cockroaches, helping to control the population of an insect that very few people, even the most tolerant, will relish having in their homes.

Dear Daniel Marlos,
Thank you for your fast reply. I need to work in my id skills! Good that I leave it alone as I normally do with insects (with the exception of cockroaches).

Letter 13 – Ensign Wasp from Ghana


Subject: Strange fly – Accra Ghana
Location: Accra Ghana
February 25, 2014 9:53 am
Live in Ghana, west Africa, these bugs keep appearing in my bedroom, never seen them before anywhere else. I’ve lived in the US before and never saw them there either. My biggest concern is if it is harmful, like carry some disease. Please help! Thanks
Signature: ND

Ensign Wasp
Ensign Wasp

Dear ND,
This is a Wasp, not a Fly, and it does not carry disease.  We are surmising that once we tell you that this is a beneficial Ensign Wasp that parasitizes the ootheca or egg cases of Cockroaches, helping to reduce their populations, that no additional individuals will fall victim to Unnecessary Carnage.

Dear Daniel,
I really appreciate the information and advice, especially knowing how much you have to work on each day.
I also want to assure you that these wasps will no longer suffer at my hands.
Best Regards

Letter 14 – Ensign Wasp: Cockroaches, Pesticides and Asthma


Subject: Please help me identify this bug.
Location: South Florida
April 12, 2014 7:44 pm
I live in South Florida and I keep noticing these bugs inside of our apartment. It just started happening around February. They have wings although I’ve never seen them fly. We get sprayed by the exterminator in our apartment so I think I’m seeing them after they have been poisoned. They also have long back legs. Please help! I have an infant and a two year old this worries me. Thanks !
Signature: Concerned Mom

Ensign Wasp
Ensign Wasp

Dear Concerned Mom,
You should be concerned, but not because of this insect.  This is a beneficial Ensign Wasp, a species that lays eggs on the oothecae or egg cases of Cockroaches.  Developing Ensign Wasp larvae eat Cockroach Eggs and unhatched nymphs, helping to control the Cockroach population naturally, without the use of pesticides.  These dead Ensign Wasps are either the result of collateral damage due to spraying for Cockroaches, or they are the result of bug phobia.  Some folks believe any bug in the home is a problem, resulting in unnecessary spraying of potentially, environmentally toxic chemicals.  We believe that the use of pesticides in the home is much more harmful to infants and toddlers than an encounter with a beneficial Ensign Wasp which is not capable of stinging nor biting a human.

Thanks so much for your reply. When we first moved into our apartment we found out it was infested with cockroaches. They tried several different sprays and treatments finally the apartments pest control sprayed a bed bug spray that was extremely strong smelling all through the house. I don’t see cockroaches anymore except dead on occasion, but I see these often. Does it mean I still have a cockroach problem too? Is this something I should consider breaking my lease for because of my children? Thanks again for your reply.

Hi again Concerned Mom,
We do not want to provide any advice regarding relocation, but we can provide you with additional information that might help you make up your own mind.  There are several studies that link Cockroach infestations to asthma in humans.  According to the American Lung Association website:  “Cockroaches, those unpleasant and unsightly pests, are not just a problem to look at. They also produce substances, or allergens, that aggravate asthma and cause allergic reactions in people who are sensitive to those substances. The allergens produced by cockroaches are likely concentrated in their fecal matter and in fragments of their body parts. These tiny particles can become airborne and contaminate the air in your home.”  The site has much more information on the relationship between Cockroaches and asthma.  The pesticides versus the cockroach infestation seems like a choice between the lesser of two evils, and there are probably differing opinions on which is worse.  The Ensign Wasp continuing to manifest its appearance in your apartment is a good indication that the Cockroaches are still present, albeit unseen.

Letter 15 – Ensign Wasp


Subject: What kind of bug is this?
Location: Coral Springs, Florida
December 28, 2015 11:44 am
I have found several of these, of various size, inside my house. You may not be able to see in this picture, but they do have wings. The sightings are sporadic with maybe a few weeks in between. We live in South Florida.
Signature: Michele Myers

Ensign Wasp
Ensign Wasp

Dear Michele,
If you are finding similar creatures in different sizes, you may be dealing with more than one species, but the insect in the attached image is a beneficial Ensign Wasp.  Ensign Wasps parasitize the oothecae or egg cases of Cockroaches, helping to control populations of what many folks consider to be household pests.

Letter 16 – Beneficial Ensign Wasp Hammered to Death in Florida


Location: Tampa, Florida
September 10, 2016 8:05 pm
Ok, so I am a little freaked out because I keep seeing these bugs suddenly and I have never seen them before. I have lived in Florida all of my life and suddenly in the last month or so, this bug keeps showing up. It doesn’t look so scary in the photo, but I will tell you that these bugs do not kill easily. And what I mean by that, is that I have to use a hammer smashing this bug into the tile floor to kill it. No amount of crushing it will kill it unless I use something like a hammer. That is freaking nuts! So yeah, they look kind of like a mosquito, but this thing is hard as a rock. The photo I am submitting makes this thing look like nothing has really happened to it and this was after using a hammer on it. Please help! I would really like to know what these things are and if I can take any measures to get them out of my house and out of my life!
Signature: Thank you!!!!

Ensign Wasp Carnage
Ensign Wasp Carnage

This is an Ensign Wasp, and we are going to unashamedly tag this posting as Unnecessary Carnage.  Ensign Wasps parasitize the oothecae or egg cases of Cockroaches, so we have to include them in the beneficial insects camp.  Large populations of Ensign Wasps in your home means that you must have Cockroaches to support the population.  If you prefer Cockroaches in your house to Ensign Wasps, then by all means, hammer away.

Thank you so much for getting back to me!
So I don’t need to worry about these bugs bitting me or anything?

Though we have always maintained that Ensign Wasps do not sting humans, we believe there is a comment somewhere on our site claiming that a sting occurred.  Suffice to say that they are NOT an aggressive species, though handling one might result in a sting.  They do NOT bite.  According to Owlcation:  “The Ensign Wasp (Evonia appendigaster) looks a bit like a black spider with wings. Many people, upon seeing one, might assume that it will sting, but in fact it is totally harmless.  The Ensign Wasp is actually a beneficial insect because it is a parasite of cockroaches and hunts for their egg-cases, which are known as oothecae. The female wasps lay their eggs in them and the wasp larvae eat the cockroach eggs.”  The Galveston County Master Gardeners website has a nice page devoted to beneficial species and stinging is NOT mentioned.

I can’t tell you how much this means to me to get this info.. It is my goal to live in harmony with the earth and its population, even those bugs that freak me out. I really wanted to call an exterminator, but I am thinking it is best to just leave things be. Is there a way for me to donate to you via paypal? Thank you again!

That is very kind of you Andrea.  There is a Paypal link on our site.


  • Bugman

    Bugman aka Daniel Marlos has been identifying bugs since 1999. whatsthatbug.com is his passion project and it has helped millions of readers identify the bug that has been bugging them for over two decades. You can reach out to him through our Contact Page.

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  • Piyushi Dhir

    Piyushi is a nature lover, blogger and traveler at heart. She lives in beautiful Canada with her family. Piyushi is an animal lover and loves to write about all creatures.

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81 Comments. Leave new

  • I was wondering how big these can get. There was a bug that looked exactly like this in our house but it’s about 1 1/2 inches long (body only – legs much longer) and when I was reading about these they’re smaller. Also, if that’s what we had, does that mean there are cockroaches nearby? We’ve lived here 9 years and I’ve never seen one so this has me worried. Thanks for your help.

  • Thanks for the info. Caught similar critter in my apt, and was ready to release it outside, but seeing as my multi-unit building has the big black beasties roving about, I’m going to adopt the Ensign, and hope she does her deed on them.

    All of the mentions of this critter show it living in the Southern US. Anyone have an explanation of how it happens to be up here in Chicago?

  • Gee some people are so touchy. Once captured they could easily have been photographed and identified without killing them since you “had one in a bag for a whole day”and then you could have educated your son about beneficial insects so he wouldn’t be so scared in future. Thankfully you point out this is a one time exchange so we won’t have to see your unnecessary carnage popping up again.

  • I agree with Trevor and Bugman. When I read that the teacher kept live creatures in a bag with no air for hours I was shocked. Why not just let them go outdoors. Seems like that would be a nice lesson in compassion for the child.

    • Thank you Laura, for your interesting perspective on what might have become a marvelous learning experience in both science, pesticide free pest control (Cockroaches are rumored to be associated with asthma in children, and we suspect use of pecticides might be the true catalyst for the syndrome), and social skills.

  • OH no, she killed an insect, the world is gonna end! I agree, you did seem to be kind of rude to her. I’m all about getting educated about what this or that is in the house but if I encounter something in my home that appears to have a stinger, whether it does or not, whether beneficial or not, I’m going to kill it and then find out what it is. If its not harmful, I’ll decide next time whether or not to kill or catch and release…. Anyway, I had to register and comment because of how people are acting over killing a bug. How many insects do you murder everytime you drive your car… wow

    • In hindsight, we probably were a bit sarcastic. You might enjoy this old posting entitled Car Grill Road Kill. Our editorial staff commutes using public transportation, but trains and buses don’t break for bugs either.

    • I liked the way she played both the teacher and the mommy cards to justify her worldview of fear and cruelty.

      I also liked the way she colonized her son’s interest while spanking The Bugman as though he were a six-year-old who should crumple at her mighty mommorial authority.

      Once upon a time people said, “It’s just a slave, who cares?” “It’s just a dog/cat/horse, who cares?” “It’s just a river, who cares?” “It’s just a pit mine, who cares?” “It’s just a permanently irradiated desert, who cares?”

      “It’s just a bug, who cares” is more of the same thinking: human ignorance and ego that quickly justify their actions, slap down all challenges to their assumptions, and cut off the bearer of viewpoints they don’t wish to hear.

      I’d hate to have my tax dollars paying THAT teacher’s salary.

    • I liked the way she played both the teacher and the mommy cards to justify her worldview of fear and cruelty.

      I also liked the way she colonized her son’s interest while spanking The Bugman as though he were a six-year-old who should crumple at her mighty mommorial authority.

      Once upon a time people said, “It’s just a slave, who cares?” “It’s just a dog/cat/horse, who cares?” “It’s just a river, who cares?” “It’s just a pit mine, who cares?” “It’s just a permanently irradiated desert, who cares?”

      “It’s just a bug, who cares” is more of the same thinking: human ignorance and ego that quickly justify their actions, slap down all challenges to their assumptions, and cut off the bearer of viewpoints they don’t wish to hear.

      I’d hate to have my tax dollars paying THAT teacher’s salary.

  • I saw one of these today.,. Snapped some pics and looked it up… What an amazing creature! I mean, how do they find those eggs?! I hope I see it, or more, so I can show my kids, they will love it! Natures Raid lol

    • We suspect a female uses the senses that are controlled by her antennae as well as sight to locate Cockroach ootheca.

  • Wow! These insects are incredible, they are now my favorite insects having in mind that they get rid of those roaches,I believe this information should be posted on the local news so we the people can cooperate with this insect.

  • There is one of these in my kitchen!
    I know it is harmless but I have a crazy phobia of insects (stupid, I know)

    Will it sting a human if annoyed??

    I don’t intend on killing it but if it comes near me I might swat it away from me out of fear!

  • There is one of these in my kitchen!
    I know it is harmless but I have a crazy phobia of insects (stupid, I know)

    Will it sting a human if annoyed??

    I don’t intend on killing it but if it comes near me I might swat it away from me out of fear!

  • Was indeed stung....
    August 23, 2014 8:30 pm

    I was just stung by one of these 10 minutes ago. Some how it got into the bathroom and was hanging out inside my towel. Was unaware of it until it stung me on the side of the stomach. It was indeed a sting. I have a slower acting allergy to Yellow Jackets, but don’t seem too phased by other wasps. Hope a trip to the ER isn’t in order this evening!

    • Thanks for letting us know.

    • I got stung by one too it’s not too bad. I have anaphylactic reaction to all bee stings but this one produced no reaction, thank the Lord.

    • Stumbled upon this looking for info on these little guys, And Oh my goodness me too! (7 years later on this thread, lol) I was drying off with a towel and I looked down and he was on my chest and stung me. It triggered a mild anaphylactic reaction. I have mastocytosis so I react poorly to such things. Triggered all over body hives, super itching, and small cutaneous lesions around the bite area. We live in Northeast Texas. Good to know I am not the only one.

  • Yes they can sting. I was just stung on the hand by one.

  • I was stung this weekend. It’s doesn’t hurt as bad as a bee sting.

  • I see these at the Baton Rouge zoo sometimes. At first I always think it is an injured wasp with no tail till I get a closer look. They are really incredible. Thanks for the info.

  • I live in New York and recently these wasp/fly insects are spotted about a month ago in my kitchen and bathroom. This is the first time I have encounter them. Is it common for them to be
    in the New York area?

  • I live in New York and recently these wasp/fly insects are spotted about a month ago in my kitchen and bathroom. This is the first time I have encounter them. Is it common for them to be
    in the New York area?

  • Em minha casa tem muito destas vespas mas tem barata já fiz de tudo mas elas estão me vencendo o que faço para minimiza está infestação obrigado

  • I beg to differ. I was stung or bitten by one this morning on the bottom of my foot. Felt like I stepped on a piece of glass.

  • dongswatter
    May 26, 2016 6:31 pm

    You guys are assholes who gives a shit about that ugly ass bug there are plenty left.

    • Dear Dongswatter at Cheesepooter33,
      There is no need for us to call you any names because you have done a much better job than we ever could at giving yourself childish, scatological pseudonyms.

  • Savannahs Mom
    June 17, 2016 5:54 pm

    My 11 month old daughter got stung tonight on her little thumb. I think she may have tried to pick it up and it stung her. There is a little spot with blood underneath maybe it was a bite? An way she howled and her thumb is swollen! Hoping a trip to the ER wont be necessary, the bugs life ended.

  • Ensign wasps DO sting. I have been stung on several occasions. Didn’t know what was stinging me until I found the bug. Assumed they were spider bites . I am allergic to insect bites & stings, and am especially sensitive to spider bites. I was stung 4 days ago and ended up in the ER this time. Apparently the wasp was caught on a seam inside my tank top and couldn’t get loose.. What appeared to be 1 huge bite turned out to be 8 separate stings. It is still swollen and sore.

    • My daughter was stung 3 times!!! Her foot is huge!!! The insect was in het bed? Been giving benadryl

  • I have a giant fear of parasitic anything, and I’m also sorry to say that coming across this bug, I killed it. It looked like a spider, and it could fly — I just don’t like bugs. However, I want to learn more about this bug; do they lay eggs in humans? Could it be possible to use humans as a subsitute? If I found one, is there more to follow? Please answer, I know its harmless, but still…

  • “If you prefer Cockroaches in your house, by all means, hammer away.”

    You just made my day with that remark LOL!

  • “If you prefer Cockroaches in your house, by all means, hammer away.”

    You just made my day with that remark LOL!

  • I have been stung twice by Ensign wasps when i was doing research on them.

  • Not biting is a very big lie, I was bitten by this insect before and its painful.

  • I was bitten too. It’s become red like a pimple. First it stung me below my wrist, when I flapped it off, it got me above my knee. It keeps inflating n deflating since the bite. It seems every time I eat or drink something it reacts n inflates, itches n deflates again. Except water.
    Wajeeha from Karachi, Pakistan

  • I was bitten too. It’s become red like a pimple. First it stung me below my wrist, when I flapped it off, it got me above my knee. It keeps inflating n deflating since the bite. It seems every time I eat or drink something it reacts n inflates, itches n deflates again. Except water.
    Wajeeha from Karachi, Pakistan

  • I often see these flying around indoors and one has never come near me or paid me any attention. If they do sting id say the chance of that happening is pretty small.

    • They do sting I promise you, my wife has an extremely high pain tolerance and if she says it hurts you better believe it will hurt. She had one crawl up her pajamas and bite her on the back of the knee. She has had pain in her legs since she had Covid ,but after the stings initial pain she said it bit her or stung her again and after awhile her leg pain from the Covid virus went away for a few hours. I asked her if the pain from the sting was worth the break from her leg pain that is constant since Covid and she said “hell no that shit hurt bad” so take that how you want ,but I know my wife and if she said it hurt that bad I will be killing everyone I see in my home.

  • Thank you for the post. It was very useful!

  • They do, or will, sting. One flew into my hair while sitting on my couch. I swatted at it while jumping out of my seat, and apparently knocked it down onto the couch cushion. When I couldn’t detect it flying around anymore, I sat back down on my couch. A couple of minutes later I was stung right through my shorts. I sprang off the couch and the little bugger flew off from where I was sitting.

  • Mario German
    May 31, 2017 5:15 pm

    Can it also eat bed bug eggs?

  • Mario German
    May 31, 2017 5:18 pm

    Do they also eat bed bug eggs?

  • I’ve got several of these guys in the yard and house. I let them land on me and crawl. They seem curious and intelligent. They’ve not stung me, and as long as they don’t mess with my pet spiders and tarantulas, they’re welcome to stay. I adamantly refuse to use insecticides or chemicals in or around my house. It’s better for everyone that way.

  • well I got news for you they do attack ,bite/sting humans.
    I terminate them with extreme prejudice and no mercy because of it.
    I backfist them against concrete walls.
    Best to stun them first with windex so they can’t fly away, then stomp your heart out. sweet revenge

  • well I got news for you they do attack ,bite/sting humans.
    I terminate them with extreme prejudice and no mercy because of it.
    I backfist them against concrete walls.
    Best to stun them first with windex so they can’t fly away, then stomp your heart out. sweet revenge

  • I’ve gotten stung/bitten by one 3 times on my left arm. It seemed to swell up to a large size, and by placing an EXTREMELY hot wet towel on it for a period of time on it seemed to help with the itching. After a day or so it went away. I know that it was definitley not any other bug. I spent a long time looking it up to find out that it was indeed a Ensign Wasp. But it said that “they don’t sting” and that they are “harmless” and that “they kill roaches” which is in my opinion mistakenly false. I believe that they kill roaches, but they do sting. There are reports^^ of people being stung.

  • I saw the other site that you are reffering to, the one with the comment of how that person got stung. But you aren’t acknowledging the other comments about being stung multiple times. I’ve been stung 3 times by this insect and it is Very painful. I placed i EXTREMELY hot wet towel on the stings for a long period of time and it went away after a few days.

  • I believe they do go after cockroaches. I live in a run down apartment building and have to deal with a bad roach infestation every year. After being stung by an ensign wasp last year, I started killing every one I saw. May have been a mistake since the roach problem is ungodly this year.

  • Jimmy Hicks
    June 7, 2018 6:55 pm

    Thanks for the help with the ensign wasp

  • Jimmy Hicks
    June 7, 2018 6:56 pm

    Send me more information thank you

  • He got my niece on her toe. Clean the sting with peroxide and have her taking a Benadryl to be safe…

  • Yes, it’s proven to sting! My 2 year was stung and I was sure that was it., I have seen it lately in the main bathroom floor or bath mirror, even on top in my master bedroom ceilings. My child’s ear swell up and it obviously was a sting. Next morning found a dead one in the very bed.

  • Clint Blackwelder
    August 25, 2018 3:54 pm

    Stumbled across this after eliminating what I first thought was a housefly, but on some intense steroids. On closer examination the distinct wasp-like abdomen made me curious. Now I am kicking myself for shooting first and asking questions later. If I see another one, I’ll leave out a tin of water and a welcome mat. Thanks for the info.

    Spotted 08/25/2018 Jacksonville, Fl 18:30

  • I forgot our local name for the Ensign wasp and was searching for it and after 7 years I bumped back into this page.
    I even forgot about this. A very nice surprise!
    You can forget my request for making the pictures copyright. I am more than happy to have helped your website with these pictures. Keep doing what you do, this site is awesome!

  • I forgot our local name for the Ensign wasp and was searching for it and after 7 years I bumped back into this page.
    I even forgot about this. A very nice surprise!
    You can forget my request for making the pictures copyright. I am more than happy to have helped your website with these pictures. Keep doing what you do, this site is awesome!

  • Kasey Tucker
    June 3, 2019 5:23 pm

    My husband was just stung by one of these but I am so glad to know what they are now. Thank you for the identification help!

  • I caught and released 2 in my apartment. The first one flew by my arm and later I stepped on (but didn’t shmoosh) with my foot. Neither stung me, but they definitely look like flying spiders which is enough for me to get them out fast.

  • in my house there were 2 big Ensign Wasp and they made a huge nest on our lamp when we wanted to go upstairs and down stair they were attacking jumping off their huge nest and running to attack us. Luckily no one of us got stinged but these creatures were waking us up in the morning because they were making a loud noise when they were flying close to us. Then one day we destroyed their nest when they were gone and now one year later they are back. Pls i need advise for how to get rid of them.

    • James Sorensen
      October 6, 2019 11:30 am

      I was stung about 16 times one nite looked like pimple I scratched some of them and they got worse took a mounth to finally go away left little round scare

  • I also live in NYC and found two at work! 1 in the bathroom and one in the office on the window. Does anyone know if this is common here? They’re doing construction so maybe these bugs came to eat the cockroaches that might’ve been lurking and coming out bc of the work going on?… I’m really curious!

  • Kim Montgomery
    August 8, 2019 7:44 am

    Hey if they paratiize cockroach egg capsules then I will worship them till I die!

  • James Sorensen
    October 6, 2019 11:37 am

    I got stung 14 times one nite left a pimple like sore that when scratch it got worse like a spider bite took a mounth and a half to heal still little scare found it my bed next day hard to kill never thought they could sting wrong they hurt

  • Ensign wasps absolutely do sting humans and it hurts bad. There was one inside the house and it landed on my leg. It stung the crap out of me. It burned like fire. It is so infuriating to constantly read that the do not sting.

  • I’m glad to FINALLY find an online source where other people have also been stung/bitten by these fellows. All those articles that say ensign wasps can’t hurt people clearly have never been in close contact with one. A year ago, I was laying on my bed reading when I felt a sharp pinch on my foot and saw one of these wiggly-butt jerks skittering away. I regularly take bugs outside, but ever since this one left a small welt on my foot, ensign wasps get the shoe now.

  • April Crouch
    June 29, 2021 4:22 pm

    I found this thread while researching this insect after my 4 year old got stung. We had come back in from outside, and laid in the floor then it turned into a panic painful screaming and the bug was where he was laying, I put it in a bag in case he had a reaction. But within minutes and an icepack to the right butt cheek, he was better. We will release the bugger into the wild. There is a sting mark on his butt

  • I wonder if the insect that these commenters said were stinging them were actually an ensign wasp. I found one in my house and captured it and provoked it to sting me but it still didn’t.

  • Martha…
    You stepped on. The poor little animal was not to blame! They are harmless to humans, they won’t attack us.

  • I. M. NotFoodForYourBabies
    May 12, 2022 12:02 pm

    I also live in Florida and these things suddenly started showing up I think three years ago. They are not harmless, one laid eggs in the soft flesh just inside my lower eyelid and I woke up as it was flying away. I was not sure what was going on with my eye [a large bump inside] so I put a qtip dipped in iodine against the bump and about 6 eggs [in the form of a circle]came out of the flesh. While I wholeheartedly approve of parasitical activity on cockroaches, unless they leave when prompted, I will continue to smash them until they are dead if they are uncooperative!

  • Catherine Cato
    May 30, 2022 12:07 pm

    I have been seeing these in my house for the last couple of years. Something told me to leave them alone. The cats have begun to leave them alone. They don’t populate uncontrollably, there are only a few. I noticed the fly population has dwindled. Thanks for helping me identify what they are.

  • Sachin Mukundan
    October 11, 2022 7:15 am

    Hi team,

    Since I read the good things, about ensign wasp.

    Just a query out of concern as a parent.

    My 11 month old son just put one of the ensign wasp in his mouth for few seconds and as we noticed him, trying to munch, we saw it we immediately removed out from his mouth.

    Is is it something to be worried about, like some mouth ulcers or infection

  • I couldn’t stop reading. It’s that engaging!


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