Assassin Bug

2007 October 27

This one is an assassin bug. It’s actually in the same family (Reduviidae) as the Thread-Legged Bug from last week, but it certainly doesn’t look like it:

Specifically, I think it is Reduvius personatus, commonly known as the “Masked Hunter”.

When I found it crawling on the bedroom window, it didn’t move very fast, and didn’t look like an aggressive predator, so originally I thought it was one of the plant-sap-sucking bugs[1]. Specifically, I thought it might be a Squash Bug, which looks similar but not identical. I understand that the most visible difference is that the assassin bugs have a distinct “neck” while the squash bugs do not.

The antennae are very long, I had to take a special photograph to fit them in. There are actually only a few segments in the antennae (it looks to me like there are only 4, as compared to what look like sometimes over a dozen for other insects), so they aren’t particularly flexible.

Like all true bugs, they have piercing/sucking mouthparts, so instead of chewing up their prey they have to suck out their juices. They may inject digestive fluids into their prey to liquefy their innards first, like spiders do, but I don’t know for sure[2].

Reduvius personatus is commonly found in houses, like this one was. The adults are pretty easy to spot, but the nymphs often aren’t – they have sticky bodies when they are young, and collect lint and other debris until they look like little dust balls. So, if a “dust bunny” under your furniture moves under its own power, it might be a live one, and could bite. Mostly they don’t bite people, though — they prey on other small insects that they find around the house. Interestingly, they are reported to be pretty effective predators of bedbugs, so they might actually keep you from being bitten.

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[1] As a result, I confess that I didn’t handle it very carefully. It didn’t bite me, though. Just lucky, I guess. Incidentally, S_ says that one of these days, I’m going to have to write something like “The bite of these insects is, as advertised, extremely painful”, or, even worse, “I must apologize to my wife for telling her that this one was probably harmless . . .”

[2] On further checking, I see that yes, Assassin Bugs do use external digestion. This would certainly account for their reputation for having excruciatingly painful bites. I think arthropods are ideally suited for being eaten this way. The exoskeleton makes a nice, solid, relatively inert shell to hold the injected digestive fluids in while the innards are liquefied, and then the predator can just suck it all up and throw away the chitinous husk. Convenient.

4 Responses leave one →
  1. Mara permalink
    June 13, 2012

    Hi! I live in Michigan. I was bitten by one of these. Do I need to be concerned about Chagas’ disease or does this particular assassin bug not carry it. (This is the exact insect that bit me, it’s sitting here in a baby food jar staring at me) any help you could give me would be wonderful. Thank you!

  2. June 13, 2012

    Mara: Nothing to worry about. These aren’t the bugs that carry Chagas disease. And even if they were, they would have to first bite someone who has the disease, and then bite you. Since this particular species of bug generally only bites humans if provoked (they prefer to eat other insects), it would be vanishingly unlikely that a given bug would ever bite two people in its lifetime. I’d have to say that the chances of catching Chagas in Michigan from one of them are pretty much zero.

  3. Josiah permalink
    July 7, 2013

    Just found one of these in our house in south east Michigan.
    I stumbled across your site while searching around to identify this bug. Your pictures and description were very helpful. =)

  4. July 8, 2013

    Josiah: I’m glad you found it useful!

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