46 Milkweed Assassin Bug Facts: Brutal Insect Executioners (Zelus longipes)

Looking to learn more about milkweed assassin bugs? You're in the right place! These guys are pretty freaky, and we've got everything you want to know right here. So read on if you want to be amazed.

Milkweed assassin bug

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46 Milkweed Assassin Bug Facts

With “assassin” right there in the name, you probably expect the milkweed assassin bug to be a ghastly murderer.

You'd be right.

Though they're mostly harmless to humans, milkweed assassin bugs are brutal executioners when it comes to other bugs. They can wrestle down beetles and butterflies up to six times their size, and when they're ready to eat, they inject a flesh-melting venom into their victims that literally liquefies their insides.

It's pretty gross, right? But we're just getting started. Keep reading these milkweed assassin bug facts to learn more about nature's long-legged killing machines.

1. What is a milkweed assassin bug?

Milkweed assassin bugs are relatively common insects that are found around homes, gardens, farms and crop fields.

They can be quite helpful to local ecosystems, but they can also deliver painful bites when they're feeling threatened. If you've noticed milkweed assassin bugs around your tomatoes, it'll be up to you to decide whether or not their benefits outweigh their bites.

2. What does the milkweed assassin bug look like?

The milkweed assassin bug has a very distinctive appearance. As part of the “assassin” family, it has long, spindly legs and even larger and spindlier antennas. It also boasts a sucking mouthpiece that allows it to drink down its prey after liquefaction.

Facts about milkweed assassin bugs

The most notable feature of the milkweed assassin bug, however, is its coloring. It has a bright reddish-orange body with black limbs, so it definitely stands out when it's perched on a leaf.

If you take a closer look, you'll also notice “wing pads” on its back. These aren't true wings; they never mature past the beginning stages of development and they won't support the milkweed in flight. But they're more than just black spots!

3. How big is a milkweed assassin bug?

It depends on the gender of the bug. Males usually measure around 16.1 – 16.8 millimeters while females hover around 18.2 – 18.4 millimeters.

As you can see, males are smaller than females. Males also have rounder torsos while females are flatter or plate-like.

4. Why do milkweed assassin bugs have sticky legs?

They aren't sticky all of the time! The legs of the milkweed assassin bug are covered in short, pointed hairs like sundew plants. These hairs are used as grips for a sticky resin that the bugs can produce from glands on their front legs.

They spread the resin around their limbs to create a sort of glue trap that can be used to catch and immobilize their prey.

5. How many types of assassin bugs are there?

There are more than 7,000 species of assassin bugs.

They belong to the reduviidae family, and they're famous for their gruesome killing methods when they hunt. Some of them even feed exclusively on blood like a leech.

6. How can milkweed assassin bugs be distinguished from other types of assassin bugs?

Have you spotted some long-legged, leaf-crawling bugs in your garden? Are you wondering if they're milkweeds or something else entirely? Here are a few ways to tell:

  • What do they look like? Assassin bugs can have drastically different appearances. For example, while the milkweed assassin bug has a bright, vivid color, the masked hunter assassin bug is brown-bodied to help it blend into sand and dirt.
  • How do they eat? If you catch them in the act of feeding, that can tell you a lot. Milkweed assassin bugs hold their victims close and use their suckers like vacuums, but other species like to crush their prey or consume them whole.
  • What do they eat? If they eat anything other than insects, they aren't milkweeds. Milkweeds are notoriously uninterested in leaves, bark, bushes and other staples of bug diets.
  • Did they bite or sting you? Did they try to suck your blood? Milkweed assassin bugs are semi-afraid of humans, so they'll only deliver a quick defensive bite and move on, but other species might be more aggressive. Do some research on their behavior to figure out which type of bug that you have on your property.

7. How did the milkweed assassin bug get its name?

Milkweed assassin bugs get their name from their resemblance to regular milkweed bugs (oncopeltus fasciatus).

Milkweeds have the same orange-and-black coloring, and they're found in the same regions of Central and South America. It was probably inevitable that their long-legged cousins were named after them.

8. Are milkweed assassin bugs aggressive?

Yes and no. Milkweed assassin bugs are ambush predators with a swift execution style, so they can be quite aggressive when it comes to catching and killing their prey. They don't live leisurely lives.

On the other hand, milkweed assassin bugs don't pose a threat to humans. They bite, but that's only if you disturb their territory. They won't bother you if you don't bother them.

In fact, unless they're guarding their egg clusters, most milkweed bugs will scatter when you get too close. It's hard to classify this kind of creature as “aggressive” since they're so reactive instead of offensive.

9. Do milkweed assassin bugs bite?

Yes. Milkweed assassin bugs will bite humans when they're feeling threatened.

Normally, they'll use their beak-like sucker to puncture their prey and drink their insides. While they won't liquify your insides, the exact kind of bite you receive will depend on the exact kind of circumstances.

10. Are milkweed assassin bugs harmful to humans?

Milkweed assassin bugs can deliver a painful bite thanks to the venom found in their saliva. It's so powerful that it can literally melt the tissues and organs of other insects into liquid form.

Humans, on the other hand, are made of stronger stuff. You'll feel a sting from the venom, and it might cause a painful lump under your skin for a few days, but that's about it. It won't have any long-term consequences for you. You aren't an earthworm!

11. Are milkweed assassin bugs dangerous?

To other insects, milkweed assassin bugs are harbingers of doom. They'll prey on anything and everything that lives in a garden or vineyard, and they can win fights against creatures much bigger than themselves.

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There's a reason why milkweed assassin bugs have to hide before they strike. If they were out in the open, other bugs would flee from them as a matter of course.

12. Are milkweed assassin bugs bad for monarch butterflies?

Milkweed assassin bugs prey on caterpillars, so they aren't great for monarch butterflies. However, they don't target them any more than other species.

This is sometimes a point of confusion for people who expect milkweed assassin bugs to act like regular milkweed bugs: both milkweeds and monarchs live off the milkweed plant, so if resources are scarce, they can be in direct competition for the same food supply.

Milkweed assassin bugs, on the other hand, don't care about milkweed plants at all. They were only named for their superficial resemblance to milkweed bugs.

13. What do milkweed assassin bugs do?

Milkweed assassin bugs aren't always a nuisance. Some people will even breed or deliberately introduce them to their landscapes. They're used for a very specific purpose: pest control.

You see, milkweed assassin bugs will eat pretty much any insect that they come across. They aren't picky. Whether it's a corn silk fly or a big, juicy beetle, they'll make a meal out of anything that crawls into their path.

This makes them ideal for farmers who don't want to resort to pesticides. Instead of spraying lots of chemicals in their fields, they can just introduce the milkweed assassin bug to the environment.

Milkweeds aren't considered an invasive species, so they won't harm anything. They won't even munch on the fruits and veggies growing out of the ground. They're only interested in other bugs.

14. Can milkweed assassin bugs fly?

Milkweed assassin bugs aren't really capable of flight. They have underdeveloped wings that won't support their body weight. They might be able to move and flutter them, but don't expect to see milkweeds zooming around your azaleas.

Milkweed assassin bug facts

15. Are milkweed assassin bugs beneficial?

Yes. They aren't without flaws, of course, but many people think that the pros of milkweed assassin bugs outweigh the cons. In exchange for the occasional bite, you'll get a natural form of pest control for your property.

16. How long do milkweed assassin bugs live?

Milkweed assassin bugs can live for several years.

They're capable of surviving the winter, something that many bug species can't do. Because of this, they have longer lifespans than some of the other creepy-crawlies in their habitats.

17. What eats a milkweed assassin bug?

There isn't a definitive list of predators for the milkweed assassin bug. It's possible that they're killed by the same mammals and reptiles as other assassin bugs, but since there are more than 7,000 species under that umbrella, the list of possibilities is endless.

18. Is the milkweed assassin bug endangered?

No. While they've never been formally assessed by conservation groups like the IUCN, milkweed assassin bugs are so commonplace that they aren't considered to be at risk for extinction. They exist in large numbers across multiple continents.

19. Why are milkweed assassin bugs called true bugs?

Most insects that get the “bug” label aren't really bugs at all. This is because “bug” is an actual species classification that doesn't extend to things like flies, bees and beetles. They have their own species.

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“True bugs” is a label that applies to the hemiptera order of insects. It includes milkweed assassin bugs as well as shield bugs, seed bugs, water bugs, flower bugs, and sweet potato bugs.

20. What do milkweed assassin bugs eat?

Milkweed assassin bugs prey on other insects. They'll consume almost any bugs in a home or garden, including flies, beetles, worms, mosquitoes, and caterpillars.

This is one of the reasons why a farmer might deliberately introduce them to his crops: They won't eat the vegetables, but they'll eat the other insects that munch on the vegetables.

21. How do milkweed assassin bugs kill their prey?

Are you sitting down? Milkweed assassin bugs have a horrifying way of killing their victims.

For starters, they're ambush animals, so they'll hide among the leaves until an unsuspecting insect wanders by. Then, when the other creature least expects it, they'll grab them with their sticky, resin-covered legs that are perfect for ensnarement.

This is when things get truly gross. With their long, tube-like suckers, the milkweed assassin bugs will pierce the flesh of their victims and inject an enzyme that liquefies their organs and tissue. When the other bugs are basically piles of goo covered in exoskeletons, the milkweed assassin bugs will suck them up through their tube.

Voila. Dinnertime.

22. Can milkweed assassin bugs take down larger bugs?

Yes. Milkweed assassin bugs are able to catch and kill bugs that are up to six times their own size! However, it should be noted that they usually prefer smaller prey.

This might be because larger prey takes longer to consume and leaves them open to danger. If their sucker is buried in their victim, it can't be used to defend them from another animal.

33. What is the milkweed assassin bugs Latin name?

The scientific name of the milkweed assassin bug is Zelus longipes.

This comes from the Latin words for “Zelus” and “longfoot.”

34. Who was Zelus, and what's his significance to the milkweed assassin bug?

Zelus was a deity in Greek mythology. He was one of the winged protectors that guarded Zeus's throne, and he was known for his strong emotions of passion, envy, rivalry, and devotion.

The word “zeal” is derived from his name. There's an entire genus of bugs named after him, and it includes the milkweed assassin bug, the pale green assassin bug, and the leafhopper assassin bug.

35. What other names does the milkweed assassin bug have?

The milkweed assassin bug is often confused with other types of assassin bugs, including “kissing bugs” that get their nickname for biting their victims near the lips.

However, true milkweeds are only classified as Zelus longipes, and they don't have any other names aside from that one.

36. What's the relationship between milkweed assassin bugs and fall armyworms?

Milkweed assassin bugs are very helpful in ridding an area of fall armyworms. Fall armyworms are an invasive species that can cause actual economic damage when they destroy large areas of crops. Milkweed assassin bugs can consume them in the caterpillar stage before they grow up and become pests.

For this reason, milkweeds are often the go-to choice for natural pest control in areas plagued by fall armyworms.

37. Are milkweed assassin bugs loud?

No. In fact, milkweed assassin bugs are so quiet that you might assume they're totally silent. You'd need an amazing amplifier to hear the tiny noises that they produce when they rub their suckers against their chests.

38. Do milkweed assassin bugs carry disease?

Certain types of kissing bugs can carry parasites, but since these are transmitted through their blood-sucking, they aren't a danger in milkweed assassin bugs. Milkweeds don't cause any known diseases or disorders.

39. Where does the milkweed assassin bug live?

The native range of the milkweed assassin bug stretches from the southern U.S. to the middle of South America.

However, they can be found in many other locations as well. Since they're so helpful to farmers, it isn't uncommon for them to be deliberately bred in agricultural environments across North and South America.

40. What is the habitat of the milkweed assassin bug?

As ambush predators, milkweed assassin bugs like places where they can hide. They're attracted to anywhere with foliage, including gardens, bushes, woods and shrubs. They've also been known to hide under porch patios or in the cracks of houses and sheds.

41. What do milkweed assassin bug eggs look like?

The eggs of milkweed assassin bugs are usually long and cylindrical. They measure between 2.0 – 2.3 millimeters, which makes them quite large for their insect family, and they're brown without any additional markings.

They look simple from the outside, but when you put them under a microscope, you'll see that they have a complex internal structure that includes everything from fertilizing membranes to temperature-controlling shells.

42. How many eggs do milkweed assassin bugs lay?

Female milkweeds usually lay around 15 eggs at a time in a densely-packed cluster. It's unknown how many clusters that they create during a full reproductive cycle.

43. Do male and female milkweeds both participate in child-rearing?

Milkweed assassin bugs grow up so quickly that there isn't a lot of child-rearing for mom and dad to do. However, both parents play a role in protecting the eggs when they're at their most vulnerable:

  • The females hardly ever leave their egg clusters. When it's feeding time, the males will bring back insects for them.
  • The males will stand guard over the egg clusters and protect them from potential threats. In one test, they stood their ground even as testers waved their hands around or mimed picking them up; milkweeds usually run from this kind of danger, but the dads refused to leave their eggs. In another test, when they were shown a realistic model of a wasp species that preys on eggs, they attacked it.

44. What are young milkweed assassin bugs like?

Young ones are called “nymphs.” They mature quickly and molt about five times before they're considered adults.

One interesting fact about juvenile milkweed assassins is that they aren't born with the glands that produce resin. It takes time to develop them. Until then, they swipe some of their mom's goo from their leftover egg sacs. How's that for family closeness?

45. Do milkweed assassin bugs hibernate in the winter?

No. They overwinter, but they don't hibernate. Milkweed assassin bugs can still be spotted crawling around leaves in temperatures as low as 30°F – 40°F.

46. Where can I see the milkweed assassin bug?

If you live in the southern U.S., seeing a milkweed assassin bug might be as simple as sticking your head out of the window.

If you're a bit further north, you might need to venture to a local animal exhibit. The good news is that milkweed assassin bugs aren't rare, so you can find them in all kinds of zoos, botanical gardens and science centers.

Milkweed assassin bug face

Drink ‘Til You Drop

Most people hate them when they bite. Other people praise them when they kill off pests that would destroy farms and gardens. No matter which side of the fence that you land on, we hope that you learned something interesting from these milkweed assassin bug facts. They're fascinating creatures despite the nasty nature of their diets!

Have any questions? Let me know in the comments!

More about Drew

Drew Haines

Drew Haines is an animal enthusiast who enjoys travel and photography. She graduated high school at sixteen and started her own business, Everywhere Wild.

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