Assassin Bug Life Cycle: From Birth to Hunting Predator

folder_openHemiptera, Insecta
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In this article, we look at the Assassin bug life cycle, where these bugs live, and where they come from

Assassin Bugs, as the name suggests, are interesting species that stab their prey before consuming it. 

They’re voracious insect predators that can help keep your garden free from pests.

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Found in many shapes and sizes, it’s difficult to recognize them due to the wide variety of body shapes they come in. 

As nymphs, too, they are very visually similar to those other insects. 

The only difference is that these bugs can deliver a nasty bite if disturbed. Let’s dive more into this species. 

Assassin Bug Life Cycle
Immature Zelus Assassin Bug

What Are Assassin Bugs? 

Assassin bugs are “true” bugs belonging to the family of Reduviidae that prey on other, smaller bugs.

Containing a wide variety of species, the names of these bugs come from the type of method they use to assassinate or kill their prey. 

North America alone is home to over 150 of these. 

Some common types of assassin bugs are the ambush bug or the wheel bug. 

The various species have distinct bodies, but all of them have narrow heads and curved proboscis, which they use to stab their prey, inject a toxin and finally paralyze them. 

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Some species of assassin bugs are known to be carriers of diseases such as Chagas disease, which can be transmitted to humans and other animals through their bites.

It’s worth noting, however, that while they feed on insect pests.

Therefore, they are an overall beneficial species; they are not considered important biological pests like some other species (the minute pirate bugs, for example). 

They are general feeders and will also eat bees, which could help pollinate your garden. 

Assassin Bug

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Types of Assassin Bugs

Some common types of assassin bugs are:

Ambush bugs 

As the name signifies, these assassin bugs kill their prey by lying in wait for an unsuspecting insect to get too close. 

They have stout, chunky bodies with well-defined, large forelegs that are hooked in front.

They can vary in color from green to yellow, tan, dark brown, and sometimes patchy (like the Spined assassin bug). 

This helps them effectively blend in with the flowers and stems on which they lie in wait. North America boasts around 30 species of ambush bugs. 

Wheel Bugs

This is the most common species of assassin bug, comprising around 150 species in the family. 

Their name comes from a spiky wheel or cog-like structure that is present on top of the insect’s thorax. 

Wheel bugs are grey in color and feed on bees, caterpillars, aphids, and other insects. 

Milkweed Assassin Bug

Kissing bugs

Kissing bugs are one insect you should stay away from! This species feeds on the blood of mammals, including humans and pets. 

They mostly bite people in and around their mouths, giving them their names.

While the bite is not painful, it can transmit parasites such as Trypanosoma cruzi, which cause Chagas disease.

Where Do They Live?

Assassin bugs are primarily tropical insects, but due to global warming, their habitat area has expanded to include some previously colder regions as well.

They are currently found in North and South America, all the way from Canada to parts of Latin America. 

While no species have been found in Europe, favorable conditions do exist, and many people have suffered from diseases typically carried by the kissing bug. 

They are generally found in vegetative areas. Some species of assassin bugs live in the soil. 

Others can be found on plants, under bark, or in crevices in rocks. They can occasionally crawl indoors as well or in other farm structures like chicken coops. 

What Do They Eat? 

Assassin bugs feed on either of the two: either they are predators of invertebrates, or they are parasites of vertebrates.

Under the former, we have assassin bugs that eat caterpillars, soft-bodied insects, insect eggs, bees, thrips, aphids, and sometimes even lizards!

Under the latter, we have kissing bugs that feed exclusively on blood. 

Common Assassin Bug

Assassin Bug Lifecycle 

Assassin bugs are true bugs and hence go through 3 stages in their life. These are:

The egg stage

Female assassin bugs lay eggs on leaves, stems, or in soil crevices. The eggs hatch into wingless nymphs. 

The nymph stage

The nymph stage goes through 5 instars. As an instar, the insect is still immature. 

Nymphs will resemble the adults, but be smaller in size and, with each molt, develop more adult organs and features.

The adult stage

After the immature stages of wingless nymphs, the final molt results in a fully-frown adult assassin bug with dual wings. 

There is no pupal stage. 

Usually, they go through one or two generations in a year. For adults, overwintering depends on the species. 

The Zelus regarding, for example, will go into overwintering as an adult. The Sinea diadema can overwinter in the egg stage. 

Assassin Bug nymph

Can Assassin Bugs Fly? 

Some species of assassin bugs, such as the ambush bugs, possess dual wings and can fly. 

However, they are poor fliers and generally do not engage in flight.

They rely on swift movement and their bite as defense mechanisms. Most adult assassin bugs will not fly and, instead, walk rapidly if disturbed. 

Frequently Asked Questions

How long does assassin bugs live for?

Assassin bugs typically live for between one and three years, depending on their environment.
They reach adult size after about six months and will spend the rest of their lives searching for prey.
In captivity, they can live up to three years if cared for properly.
Generally speaking, assassin bugs in the wild don’t survive as long due to predators, lack of food sources, and other more hostile elements that reduce their lifespan significantly.

Where do assassin bugs lay eggs?

Assassin bugs lay eggs in the soil or in other plants and debris.
Usually, the female assassin bug will deposit her eggs on the leaves or stems of nearby plants.
Some species of assassin bugs are known to hide their eggs at the base of thorns.
It is believed that predators like birds struggle when they try to reach these areas and look for an easier food source, protecting the assassin bug eggs from becoming a snack.

How fast do assassin bugs grow?

Assassin bugs grow very quickly, reaching full adulthood in only two weeks after hatching. The lifespan of an assassin bug is very short, usually lasting just a few months.
During this time frame, their growth rate is accelerated, and they can reach up to 15mm in length.
They feed both on invertebrate prey and also on nectar from flowers. As they grow, assassin bugs molt their exoskeleton several times during each stage of development.

What kills assassin bugs?

Several animals, including spiders, birds, praying mantises, rodents, smaller mammals, lizards, frogs, and snakes, feed on assassin bugs.
However, assassin bugs are a diverse group, with over 7,000 known species and 120 found in North America. So there are no single predators that can be pointed out.
Generally, these insects range from 0.2 to 1.2 inches long, meaning they will struggle against larger predators such as birds and mammals.

Wrap Up

While they are beneficial insects in the garden, an assassin bug adult can deliver painful bites if mishandled. 

And their bites can be quite painful (unless it’s the kissing bug) and even cause allergic reactions! 

You can easily distinguish these insects from others (such as the Leaf-footed bugs) through their elongated head and sharp beaks. 

In their earlier stages, some might even be brightly colored to warn predators of their toxicity.

Thank you for reading. 


  • Bugman

    Bugman aka Daniel Marlos has been identifying bugs since 1999. 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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Tags: Assassin Bugs

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52 Comments. Leave new

  • Looks like the one I found killing a bee. Here’s a link:

  • Creek Keeper
    August 3, 2011 2:23 pm

    Dear Bug Man,

    Not to worry. I love your site, and am following with facebook now too. I think it may be next winter before I get all the creatures I find now that I’m really looking ID’d. But that’s ok. Thanks for all you do here. Bugs are fun!

    Creek Keeper

  • Indeed, this is a wheel bug nymph.

  • These are wheel bug (Arilus cristatus) nymphs.

  • This little rascal is a nymph of Zelus longipes.

  • I have a tendency to think that this is a coreid nymph. I think we can see the long slender rostrum which is not characteristic of the reduviids.

  • Good call, this is indeed a wheel bug nymph.

  • I believe this is a nymph of Zelus renardii.

  • This is a nymph of Zelus longipes, the only conspicuous red and black Zelus species (in the Nearctic region).

  • Indeed, this is a milkweed assassin nymph, Zelus longipes.

  • This is indeed a nymph of the milkweed assassin, Zelus longipes.

  • From a fellow Michigander, this is definitely a nymph of Zelus luridus.

  • This is a Sinea nymph, most likely in the spinipes group.

  • Both nymph and adult are Zelus luridus.

  • Probably a nymph of Zelus luridus, but in Georgia, I can’t with absoluate certainty rule out either Z. cervicalis or Z. tetracanthus.

  • This little fellow is a nymph of Zelus renardii.

  • In New Jersey, this nymph is probably Sinea spinipes.

  • Probably a nymph of Zelus luridus.

  • Agreed on a milkweed assassin nymph.

  • This is a Zelus nymph, and in Oregon, it pretty much has to be Z. renardii. I just can’t see the abdominal spines as well as I’d like.

  • Carole Tidwell
    October 15, 2013 9:20 pm

    Do these assasin bug nymphs bite? I can’t get rid of them. They are coming in on my dog. I found one on my refrigerator this morning. I am finding them all over, mostly outside. Yet they come in and I find them on my arm. SMACK–then I kill them. Do they bite? I need information.

  • Cant wait till these guys come in. Just planted milkweed a month ago and so far I am inundated with the large milkweed bug. I hope the ladybugs and assassin bugs are on their way!

  • I got bit by this green and yellow spiky assassin thing today, and I live in Phoenix, AZ.

  • Wow! I saw the orange bug crawling along my wall the other day. I am a bit embarrassed to say how long I searched for it (googling “orange bug, six legs”), but I finally found it! And funny enough, I live in the Houston area, as well. Maybe they are common here? The first I have seen so far. . .anyway, thank you for the identification 🙂

  • Wow

  • Hi i was laying in bed relaxing and i felt something sting me, and as soon as i got up it was running away and i killed it, it looked like a beetle with a stinger on the back of it, the sting is painful i have been trying to figure out what kind of bug it was and what i need to do

  • I live in Malaysia in tropical weather and found a line of egg sacs with this tiny insects around the sacs on my grill door. At first I thought they were ants but on closer inspection they aren’t. Identified them as assassin bugs after some google research.
    I have researched on assassin bug nymphs and most of them have a bright orange abdomen.
    The one I saw did not, they were fully black similar to the one in the photo above.
    The questions is, are this bugs dangerous to humans? I live in a condo and am particularly afraid this little guys might crawl into the house and cause bites.

  • I live in Malaysia in tropical weather and found a line of egg sacs with this tiny insects around the sacs on my grill door. At first I thought they were ants but on closer inspection they aren’t. Identified them as assassin bugs after some google research.
    I have researched on assassin bug nymphs and most of them have a bright orange abdomen.
    The one I saw did not, they were fully black similar to the one in the photo above.
    The questions is, are this bugs dangerous to humans? I live in a condo and am particularly afraid this little guys might crawl into the house and cause bites.

    • While Assassin Bugs may bite if carelessly handled, they are not considered dangerous to humans, with the exception of the Blood Sucking Conenose Bugs in the genus Triatoma.

  • Give your kids a jar with a lid and a magnifying glass and let them explore!

  • I was bitten by a lime green bug that looks similar to the one above in Virginia. Can this bug cause Chagas disease?

  • Thank you! Have wondered for some time on this one.

  • Believe me… they bite and it hurts! One came into the house on who knows what but ended up on an oven mitt that rested on my counter. I picked up the mitt to quickly use it on an oven dish and the bug stabbed my hand … it was horribly painful! Now three days later it’s still tender and full of serous fluid and itchy until touched, then tender.

  • Larry Adams
    June 6, 2016 4:31 pm

    I wanted to stop and say thank you for helping me figure out what this bug is. I have been spraying them with neem oil trying to get rid of them because I didn’t know they were a beneficial insect. Now that I know, I will just let them do their thing. Thanks again from College Station, Texas

  • Earl montgomery
    July 24, 2016 2:39 pm

    I have several hundred milk weed plants, in various parts of my back yard. Are these insects going to be problems for the monark catapillers on these plants. Is this just something to put up with. This is our 4th year trying to have a butterfly garden but have noticed more of these bugs this season. We have released several hundred monark over the years and had thought these to be harmless to the monark Is there any method for controls. Thanks Earl from Bossier City, La.

    • Milkweed Assassin Bugs might prey on Monarch Caterpillars when they are young, but we cannot say for certain.

  • Hi, I live in eastern NC and I saw this bug. My dog was trying to eat it, they’re not poison are they?

  • I live in GA and had bugs like this all over my eggplant through most of the summer. I was seriously creeped out by them but they didn’t seem to affect the plant, so I put off trying to get rid of them. Decision was confirmed when I saw one of them eating some other bug. They all disappeared spontaneously around early to mid August. Now that I know they’re “good bugs”, is there a way to encourage them to come back? Also, I have a whitefly infestation and am looking for food-safe solutions.

  • I think this just bit stung me-looks so similar–it hurt really bad

  • Isn’t it the same image and signature?

  • Hi we live in England and we have just found a bug in our garden that we have never come across before can you help us with its name? Its small and black and if it gets scared all its tiny legs go under his body like the same way a tortoise does when he hides in his shell?

    • Sorry guys, we’ve sussed it ourselves it was a plain black ladybird “wow” never seen one of those before!

    August 28, 2018 2:06 pm

    Just got bit/stung by one of these 15 minutes ago. Will keep an eye on it.

  • I would not rule out a spider. They cant’ have more than eight legs, but fewer are very common.

  • Last summer i had beautiful blooms. This year my seed pods appeared in early summer and they are still present. I’ve had a huge family of baby assassin bugs and adults. I had a few blooms at the beginning of spring but none after. Whats going on with them?

  • We have a cluster of small white caterpillars on our milkweed do you know what they are?

  • Nikki Ramsell
    July 27, 2019 2:34 pm

    Bit by one in Georgia! Hurts like a bee sting!

  • Trina Slaughter
    October 25, 2022 1:01 pm

    Are milkweed assassin bugs found in Mississippi? Do they like impatiens? Are they harmful to plants or people?


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