What Do Assassin Bugs Eat? Are They Beneficial Predators?

As the name suggests, assassin bugs are prolific killers. But this ability to kill most other insects can be beneficial in your garden too! So, what do assassin bugs eat? Let’s find out.

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Despite their notorious image, If there is one variety of bugs that everyone needs in their garden, it’s the assassin bugs.

Notwithstanding the ominous name, the assassin bug is a beneficial insect that is a natural pest predator and can help protect your plants.

Almost every type of assassin bug feeds on pests like crickets, centipedes, aphids, insect eggs, grasshoppers, and spider mites.

Intrigued to learn more about what assassin bugs eat? Read on!

Assassin Bugs: What Are They?

Assassin bugs come from the Reduviidae family and are found worldwide, including Central, North, and South America, Asia, Europe, and Africa.

There are approximately 200 species of assassin bugs in North America and about 7,000 worldwide.

The most common type of assassin bug is the wheel bug (Zelus longipes), but there are several other types of bugs in this category.

There are milkweed assassin bugs, leafhopper assassin bugs, damsel bugs, big-eyed bugs, ambush bugs, and so many more!

What Do They Look Like?

Assassins are all predatory insects who feed on garden pests to fill their stomach. The typical features of an assassin bug include:

• A three-segmented, sharp beak
• Round and protruding eyes
• Long and tubular head with the elongated body
• Legs more extended than most insects
• They have wings, but they are not very good at flying

Apart from the above features, assassin bugs come in many colors, be they black, brown, gray, green, reddish, or pale.

Another thing to notice about them is that they are usually smaller than a half inch, but since they exist in a wide variety, it depends on what kind of assassin bug it is.

For example, the wheel bug is the largest species of assassin bug in North America. It is colored grey and has a topknot on its back that can help you distinguish it from others of their kind.

What Do They Eat?

Some of the popular insects that these bugs use as their primary food source would include the following:

• Spider mites
• Tiny aphids
• Caterpillars
• Scale insects
• Grasshoppers
• Armyworms
• Insect eggs
• Corn earworms
• Crickets
• Mosquitoes
• Beetles
• Leafhoppers
• Asparagus beetle larvae and eggs
• Insect eggs
• Mexican bean beetles and more

Even though the assassin bugs are known for killing and feeding on only garden pests, they can actually eat just about anything.

Assassin bugs have a big appetite, so they can feast upon a small beetle but also devour a giant caterpillar larger than themselves.

These bugs also feed on other beneficial insects, including bees and ladybugs.

While most members of the assassin bug family feed on garden pests, some others are bloodsuckers, like the kissing bug. The ambush bug drinks flower nectar to survive.

Some assassin bugs are aggressive hunters who actively seek their prey before they kill. However, most assassin bugs are lurkers who wait to ambush their prey instead of stalking them.

How Do They Hunt?

With their voracious appetite, the assassin bugs are always on a hunt and have some very unique hunting strategies to kill their prey.

Baiters

For example, many assassin bugs cover their forelegs with a tree’s sap to catch their prey. Some bugs, such as termite assassins, also use the carcass of another insect as bait to attract the insects or pests they wish to prey on.

Venomous

Many of these bugs also hide under the leaves or rocks and wait for their prey to show up before they pounce on them.

They hold their prey between their thick forelegs and stick their needle-like mouth to inject venom into their bodies which converts their insides into a fluid.

In this way, they can effectively kill their prey and then suck out their bodily fluids. Once they are done feeding, they leave behind the empty shell of the insect’s body.

Bloodsuckers

As mentioned before, kissing bugs, another kind of assassin bug, drink blood instead of following the simple procedure of killing their prey.

They do not eat the regular garden pests but suck the blood out of warm-blooded creatures found in barns, dog houses, chicken coops, and other woodland areas.

Kissing bugs are dangerous for humans because they are carriers of Chagas disease.

How Are They Beneficial To Your Garden?

Assassin bugs are beneficial for gardens because they naturally help humans get rid of unwanted pests.

These pests would otherwise damage or destroy your precious plants, flowers, and fruits. Thankfully, assassin bugs greatly help reduce possible infestations since garden pests are their primary food source.

They are naturally drawn to leafy vegetables, flower gardens, and orchards, often infested by common garden pests like caterpillars, aphids, beetles, ladybugs, and more.

Since many species of assassin bugs feed on these pests, they often hide under the leaves or rock to catch them at the right moment, pierce their bodies to transfer their venomous liquid into them, and suck out all the nutrients of the insect.

Even the wingless nymphs of these bugs start feeding small insects right after hatching, doing their bit to reduce plant-killing insects from the garden. 

How Can You Attract Them?

While it may take a while for the assassins to enter your garden and establish themselves there, here are a few tips for you to attract them into your orchard.

• Fill up a small pool of water in a bowl and add some rocks where the assassins can sit and drink water.
• Keep your outdoors lit since the assassins are attracted to illuminated areas.
• Entice them with colorful flowers since many species of assassin bugs enjoy sitting on them as they wait for their prey

If you use pesticides often in your garden, use only the narrow-spectrum ones. Once you find assassin bugs in your garden, try not to use pesticides at all.

Pesticides will harm both assassins as well as other pests, so it’s never a good idea to use them in your garden.

Frequently Asked Questions

Are assassin bugs good for a garden?

Yes, assassin bugs are suitable for gardens since they naturally prey on other garden pests like caterpillars, aphids, grasshoppers, etc.

They are a cost-effective and simple way to keep away most types of harmful garden pests that can hurt your plants.

What are assassin bugs attracted to?

Assassin bugs are attracted to gardens full of flowers, leaves, rocks, and other pests. They are also attracted to light.

If you want to bring these bugs into your garden, try to keep your porch lights on and make provisions for easy access to water in your garden.

What happens if an assassin bug bites you?

Assassin bugs have painful bites, but they are not harmful to humans. The most they can do is secrete their saliva into your skin, resulting in itchiness, rashes, or swelling.

If you are allergic to insect bites, then the reaction might be more severe, including hives, difficulty breathing, and even anaphylactic shock. Get in touch with a doctor immediately.

Will assassin bugs eat ladybugs?

Yes, assassin bugs feed on most garden pests, including ladybugs. In a way, this is a bad thing because ladybugs are also beneficial insects that feed on other pests.

Assassins are indiscriminate killers, so it could be a double-edged sword keeping them in your garden. They might end up wiping out all your other natural predators of pests.

Wrap Up

Assassin bugs are nature’s pest-eating machine. All you have to do is to give them the right environment and leave them to do their job.

Make sure that you do not end up killing them with pesticides. These bugs are somewhat indiscriminate killers, so make sure they don’t end up eating other beneficial insects in your garden.

Reader Emails

Assassin bugs eat a wide variety of pests, so some might consider them to be beneficial as well.

Many of our reader queries have been centered upon the idea of whether the bugs are dangerous or just harmless and beneficial pests.

Read on and learn more about these discussions.

Letter 1 – Milkweed Assassin Bug with Honey Bee prey

Assasin Bug and Bee
As everybody mentions, I too think this is an awesome site. We see plenty of ‘bugs’ in the yard and garden and the site really helps. Saw this poor bee poking around the center of the rose, only to come out from under a petal and pow, looks like the assassin but gets a big lunch. Of a couple of your pictures, I didn’t see an Assassin just like this. BTW, I’m in Houston, TX. The photo is reduced in size, but I can send the original if you want a closer look. Thanks,
W. Boyers

Hi W.,
Nice image of a Milkweed Assassin Bug, Zelus longipes. It is found in the warm Southern states and has also been reported from North Carolina and Texas.

Letter 2 – Milkweed Assassin Bug eats Honey Bee

Zeleus Longpipes enjoys a bee snack!
Dear WTB- I was outside gardening (with my camera- ha ha) and discovered this Milkweek Assassin Bug enjoying a late breakfast! He must have surprised the bee by hiding underneath the leaf of the Passion Flower Vine. Thought you might like the picture!
Luzie Benavides
Katy, Texas

Hi Luzie,
Thanks for sending in your great Food Chain image. If we ever tried gardening with a camera, we wouldn’t get much gardening done.

Letter 3 – Milkweed Assassin Bug eats Honey Bee

Bug “Eating” a Bee?
Hello! We live in Spring, TX (north of Houston) and found this on our car this morning. It seemed that the black and orange bug had “stuck” the bee…reminded me of a mosquito sucking blood. When the bug noticed us, it started dragging the bee across the car. My husband tried to blow them off the car, and then the bug flew away dropping the bee. Any clues? Our 7-year-old would love to know…so would we!!! 🙂 Didn’t see it searching the site. Thanks!
~Bridget
Oh, wait!!! I searched one more time on your site before pressing “send” and found assassin bugs and there it was! Yikes! I’ll attach the pic anyway. Thank you! 🙂

Hi Bridget,
We are thrilled you located the Milkweed Assassin Bug on our site and your photo of this Assassin Bug feasting on a Honey Bee is a nice addition to our site.

Letter 4 – Milkweed Assassin Bug Nymph eats fly

WTB?
Can you help with this one? Thanks,
Frank Trimborn
Houston, TX

Hi Frank,
What a wonderful photo of an immature Milkweed Assassin Bug, Zelus longipes. The nymph will eventually grow wings. Assassin Bugs are tireless predators that can also bite painfully if mishandled.

Letter 5 – Assassin Bug eats Cricket

Whats that Bug
Hey Bugman, caught this in my kitchen feeding on a housefly. I put him in a little bugviewer and took some pics. It stabs its prey with its needle and sucks em dry. It stabs the bugs all over rolling it around while it eats. Never flew but it has wings. Doesnt make any sounds. Walks around very slowly. Int the photot he is eating a cricket. I live in Columbia Missouri.
Nouri

Hi Nouri,
This is an Assassin Bug in the genus Pselliopus. Be careful handling your pet since they can bite and the bite is painful.

Letter 6 – Sycamore Assassin Bug Nymphs eat store bought Cricket

Assassin Bug follow up
A couple of days ago I sent a photo of an Assassin Bug, I think its in the Nymph stage. I’m keeping a close eye on the plant that has the Assassins on it. I went to the pet shop to buy some small crickets to stage an assassination. When I went to the plant, one of the nymphs had just taken another unknown bug. I took several pictures of the carnage. After a while I took off the back jumping legs of a small cricket, just pinch the upper part of the jumper and it falls off. I fed the prey to the aggressive hunter who took it immediately. While photographing the action, another Nymph joined in. It was quite the tug of war. They seemed to settle down after a few minutes and proceeded in what would be one of my worst nightmares. I hope you can tell me what kind of Assassin this is and what it may turn into. I have attached three new photos, 1 is what you consider carnage of the predators natural prey. 2 is a staged assassination of a store bought cricket. 3 A colossal battle of two creatures that may or may not be from another planet.Thanks
Danny

Hi Danny,
Thanks for sending your exciting letter and wonderful photographs. We pondered the merits of the natural predation versus the feeding intervention, and opted for the sensationalism of the “tug of war” between two Pselliopus Assassin Bug Nymphs and the store bought Cricket. Assassin Bugs in this genus are known as Sycamore Assassin Bugs.

Letter 7 – Millipede Assassin Bug Nymphs feed on Millipede in South Africa

African Assassins
Hiya from Mossel Bay, South Africa. I thought you might be interested in these assassin bug nymphs (Ectrichodia crux) feeding on a millipede. It looks so organised! Kind regards
Sally

Hi Sally,
Over the years, we have received a few truly memorable Food Chain images, and this is one of the best. Thanks so much for sending us your image of a “pack” of immature Assassin Bugs feeding on a Millipede. More research led us to a photo of an adult Ectrichodia crux, and the common name Millipede Assassin Bug. We promptly located another photo of an adult. We will contact Rowland Shelley, who identified all of our Millipedes, to see if he knows the Millipede species. Here is his response: “The milliped could be one of several things, but I’d say it’s a representative of the family Spirostreptidae, order Spirostreptida. Best I can do. Rowland”

Letter 8 – Milkweed Assassin Bug eats Ladybug

Could you please identify this insect for me?
May 21, 2010
Hi, I took this photo in the Big Cypress area of the Florida Everglades. It was feeding on a ladybug. I was hoping that maybe you could identify this insect as I am not having any luck! Any help would be greatly appreciated.
Alan Hochman
Big Cypress area of the Florida Everglades

Dear Alan,
This predator is an Assassin Bug, probably in the genus Zelus, but we don’t know the species.  BugGuide indicates between 7 and 12 species in the genus Zelus in North America.  Your individual resembles the Milkweed Assassin Bug, Zelus logipes, but the photos of that species on BugGuide do not have the striped legs and antennae that are so distinctive in your photo.

Karl finds a match
Hi Daniel. I did a quick search and couldn’t find any other species that matches this pattern. The Bugguide has many pictures of Zelus longipes and a few of them do have the striped legs and antennae. The link below has a photo of a specimen from the Everglades that looks pretty much identical (slightly different pattern on the head and thorax). It is identified as Z. longipes but there is also an interesting exchange of comments about whether it is a color variant or a separate species. K
http://bugguide.net/node/view/93032/bgimage

Eric Eaton cites same link
Daniel:
It *is* a milkweed assassin bug, Zelus longipes, though you are not alone in being confused.  Check out this image and thread:
http://bugguide.net/node/view/93032/bgimage
I would not have known either, my friend.
Eric

Letter 9 – Assassin Bug with prey, from France

Red eating bug
Location: French / Swiss border near Gex
August 1, 2011 1:52 am
Hello,
I noticed this vicious little beast whilst camping in France close to the Swiss border. I would love to know what it is. (And what it is eating!)
Signature: don’t care

Dear don’t care,
This is some species of Assassin Bug in the family Reduviidae.

Letter 10 – Feather Legged Assassin Bug from Australia

Do you know what this is?
Location: Martin, Western Australia
December 2, 2011 3:46 am
Hi,
I found this bug/insect/alien on my bed and I’m just wondering what it is. It seems to have feathers on its back legs and can do somersaults if it has to.
Do you know what it is?
Thanks
Signature: Hannah

Dear Hannah,
At first we thought that this was a Leaf Footed Bug or Big Legged Bug in the family Coreidae, but we couldn’t find it pictured on the Brisbane Insect website.  Additional research led us to a listing in our own archives that identifies this as a Feather Legged Assassin Bug or Ant Assassin, Ptilocnemus lemur.  We had originally misidentified that submission as a Leaf Footed Bug as well.  There is some helpful information on the Myrmician website.  Here are photos of mounted specimens from the Agriculture Western Australia website.  Larena Woodmore also has a very nice photo.

Letter 11 – Zelus Assassin Bug feeding on prey

Assassin Bug?
Location: Phoenix, AZ
May 1, 2012 5:13 pm
A close look at this one shows it eating a nymph.
Signature: Ranger Dan

Dear Ranger Dan,
We believe your Assassin Bug is in the genus Zelus based on photos posted to BugGuide.  We love getting Food Chain photos.

Letter 12 – Milkweed Assassin Bug eats chrysalis of a Senna Sulphur

Subject: Red Milkweed Assassin Bug
Location: Baton Rouge, LA
December 12, 2012 11:57 pm
I found two butterfly caterpillars and several chrysalis on my Cassia and Esparanza plants. One of the chrysalis was discolored and somewhat shrunken. I later observed an insect that appeared to be attempting to penetrate a chrysalis. An internet search revealed that it may be a Red Milkweed Assassin Bug, I have attached a photo of my bug on a chrysalis and the one from the internet. Please verify my findings are correct. I recently obtained some milkweed plants from a nursery to attract Monarchs.
Signature: ClydeO

Dear ClydeO,
You are correct.  This is a Milkweed Assassin Bug and it is feeding on the chrysalis of a Senna Sulphur, a large yellow butterfly with a caterpillar that feeds on Cassia.  We also believe that Milkweed Assassin Bugs might prey upon Monarch Caterpillars.

And, I was lead to believe that Monarchs have a fool-proof toxic defense by feeding solely on the Milk Weed plant.
Thanks for your response – great website.
ClydeO

Monarch Caterpillars do have some predators.  See this Stink Bug posting.

Well, this is what the Assassin Bug did to one of my chrysalis . .
ClydeO

Hi again ClydeO,
While this is sad, you should bear in mind that there are predators and prey in the insect world, and predators like the Milkweed Assassin Bug also help to control the populations of other harmful plant feeding species.

I considered that when I contemplated squashing him.
ClydeO

Letter 13 – Immature Assassin Bug eats Fly

Subject: Assassin bug preying on fly?
Location: Kingston, Ontario
September 16, 2015 3:17 pm
Hey there Daniel!
I spent the evening in a mesh tent observing all sorts of bugs – some I’ll be sending for IDs if you feel like it! A robberfly, a dragonfly, many ants, a horsefly, some sort of wasp-mimic, I think. And then, these two.
I think it’s a sort of assassin bug munching on a house fly. He has red eyes and a sort of yellow-borded red saddles on his back/abdomen.
Thanks for your time! I’m currently browsing through the posts so far – I’m on page 205 atm.
Signature: Dannie

Dear Dannie,
By comparing your image to Assassin Bug nymphs on BugGuide, we believe we have correctly identified your individual as Zelus luridus.

Letter 14 – Assassin Bug Eats Fly

Subject: Assassin nymph eating fly
Location: Amarillo, TX
April 24, 2016 7:05 am
Hey bugman!
I spotted a tiny assassin bug carrying a house fly around in our yard yesterday and wanted to share. Hope y’all are having a wonderful weekend!
Signature: Brittani Hinders

Dear Brittani,
We believe that based on this BugGuide image, your Assassin Bug nymph is Zelus luridus.

Letter 15 – Assassin Bug Nymph eats Fly

Subject: Need to know…
Location: Stoddard, New Hampshire
October 14, 2016 6:03 am
one of these little guys was walking on my pup yesterday… and today…. he is on my kitchen table… catching a couple of “straggler” flies that have got in threw a broken screen… (thank god, because i hate flies)…. WHAT IS IT? I was thinking a baby praying mantis…??? but the head? and has no front little arms like a mantis…he had a hold of that fly though………. one thing for sure….. he made me smile…. he’s adorable. his little feet!!!
Signature: Patty Marotta

Dear Patty,
This is an Assassin Bug nymph in the genus Zelus.  Though they are not aggressive towards humans, they can deliver a painful bite if carelessly handled.  Their mouths are adapted to piercing the exoskeleton and sucking the fluids from prey.  You can try capturing this Assassin Bug nymph in an overturned glass and transporting it back outside.  We will be post-dating your submission to go live to our site while we are away from the office at the end of the week.

thank you so much for the info. I’d kinda like to put him in an insect habitat….. seems everything i’ve been reading… they live 1-2 years in captivity… do you know if that is correct?
I have a couple of lady bugs in with him (DUG) right now… but he doesn’t seem interested. I’m thinking they might be too big for him? No?… i gave him a small spider yesterday… and he skawfed it RIGHT UP!!!! will he eat small crickets and meal worms?

Since Assassin Bugs are predators, we would expect them to eat any insects that move.  Perhaps the Lady Bugs are foul tasting.

thank you…. I bought him(DUG) a new home today….. complete with baby crickets and tiny meal worms…….. hope to see him eating soon! How long do you think he’ll live in the right conditions? He fascinates me… and made his appearance in my life at a very chaotic time, definitely something to keep my mind occupied…
Thanks again.

Perhaps a year in captivity.

Letter 16 – Leafhopper Assassin Bug eats Flesh Fly

Subject: Identification
Location: California valley
November 11, 2016 11:58 am
Working in California Valley and have seen a few of these insects slowly crawling around. There are flies everywhere, tons of them, but just today caught a slow mover munching on one of the flies, hence becoming a welcome addition to my home. They’ve been doing well too as they’ve left a pile of leftover carcasses at the base of their attack.
Just wondering what it is.
Thanks,
Signature: Chris

Dear Chris,
The predator is an Assassin Bug in the genus Zelus, and the prey appears to be a Flesh Fly.  We believe the Assassin is a Leafhopper Assassin Bug, Zelus renardii, based on this BugGuide image.  According to BugGuide:  “Generalist predator (despite its common name suggesting host specificity).”  Zelus Assassin Bugs seem to bite humans more readily than most other Assassin Bugs, with the exception of blood-sucking Kissing Bugs, and though their bite is not considered dangerous to humans, it may leave the bite site tender and swollen.  They should be handled with caution to avoid bites.

Thank you..  They do keep the flies at bay

Letter 17 – Millipede Assassin Bugs prey on Millipede in South Africa

Subject: millipede assassin bug
Location: Dordrecht, Eastern Cape, South Africa
January 7, 2017 11:16 pm
Bugman
Here are my images, but I am unable to load three at a time so I am going to try and send them one by one.
Enjoy!
Signature: Lollie Venter

Dear Lollie,
When you submitted a comment to a posting in our archives of Millipede Assassin Bugs preying on a Millipede, we did not imagine that your images were going to be as spectacular as they turned out to be.  They are an excellent addition to our archives.  According to Beetles in the Bush, the Millipede Assassin Bugs:  “Ectrichodia crux belongs to the subfamily Ectrichodiinae, noted for their aposematic coloration – often red or yellow and black or metallic blue, and as specialist predators of Diplopoda (Heteropteran Systematics Lab @ UCR).  Species in this subfamily are most commonly found in leaf litter, hiding during the day under stones or amongst debris and leaving their shelters at night in search of millipedes (Scholtz and Holm 1985). They are ambush predators that slowly approach their prey before quickly grabbing the millipede and piercing the body with their proboscis, or “beak.”  Saliva containing paralytic toxins and cytolytic enzymes is injected into the body of the millipede to subdue the prey and initiate digestion of the body contents, which are then imbibed by the gregariously feeding assassin bugs.”

Dear Lollie,
Thanks for sending us additional images.  We now have six of your images posted to our site.

Daniel,
The video is still in production.  Will send it as soon as it has been done.
Regards
Lollie

Letter 18 – Sycamore Assassin Bug eats Ant

Subject: Fleeing the scene of the crime…
Location: Sussex County, NJ
August 12, 2017 1:05 pm
I thought you might enjoy this one for your Life Cycle gallery. A Sycamore Assassin Nymph leaving the corpse of a small ant. Kind of hard to be discreet when wearing an orange jumpsuit…
Have a great weekend.
Signature: Deborah Bifulco

Dear Deborah,
Thanks for providing your image of an immature Sycamore Assassin Bug and the corpse of an Ant it has feasted upon.  As you indicated, it will be an excellent addition to our Food Chain tag.