Assassin Bug Nymph – Masked Hunter

2012 August 1

Sometimes “dust bunnies” are just dust bunnies. Other times, though, they move. Like this one, for example: we found this moving lint speck on the garage floor on August 22, 2010.

It was just a little guy, only a few millimeters long, covered with random dirt (the gray and brown stuff) and sawdust from our table saw (the white, splintery-looking stuff). This is at pretty high magnification, in real life it just looked like a tiny ball of dust. With antennae.

These have been on this site before (twice!), many years ago, although those were much older and larger. It’s an early-instar nymph of the Masked Hunter, Reduvius personatus.

These are a non-native, cosmopolitan species that has been carried around the world by humans. Unlike a lot of cosmopolitan species, though, they are not pests. They are predatory, and eat a lot of other, smaller insects that are pests – most famously, they eat bedbugs. I expect they will eat carpet beetles, clothes moths, and the like as well. Predators aren’t usually all that finicky about what they eat. I wouldn’t go so far as to say they are “harmless”, but they don’t go around gratuitously biting people. They’ll only bite humans if provoked by rough handling. They certainly don’t suck human blood (at least not directly. I suppose that if they eat a bedbug, then they get human blood second-hand)[1].

The adults get to be up to half an inch long, and lose their dusty camouflage on their final molt, becoming these large, black, sinister-looking individuals. Until then, though, they tend to lurk in the dust-bunnies under the bed, where they prey upon the unwary.

So, there really are monsters under the bed[2]. It’s just that they are only dangerous to you if you are only a few millimeters tall.

[1] While these tend to keep down most of the little insects that a lot of people get the willies about, I’m not so sure that such people will be comforted by the fact.

[2] I used to have a link to an illustrated story by Ursula Vernon called “Irrational Fears”, about the monsters under the bed that mostly preyed on dust bunnies. Unfortunately, it is no longer available online, although it may possibly be available in printed form. She is an artist who also writes a lot of rather unusual children’s books.

9 Responses
  1. JennyW permalink
    August 1, 2012

    So THAT’S what those bugs are! I’ve seen these things forever! Thank you! How do they stick all the debris to themselves?

  2. August 1, 2012

    Just as I was succumbing to a gentle melancholy over the speed of disintegration of the summer holidays, July having gone at the speed of a tornado through Edmonton and now August straddling us like some kind of giant King Kong, thumping his chest and warning us that school will soon be upon us and that the holidays are being tagged for capture, I came upon your photograph of this bug-in-disguise.

    Wow. Who knew that the dust bunnies under my bed could possibly be this sort of vermin? They look like moth-eaten insect models. Perhaps they could be fashion models for the insect world donning the new cutlery of torn grunge garments for us to admire.

    I would vacuum under my bed immediately but I do not want to do it. Even the thought of this potential disaster lurking under the bed with the boys’ Archie comics, the detritus of stashed odd garments and mismatched socks from the laundry basket that have made a nest under the bed, do not prompt me to get the vacuum and remove said dust bunnies /possible dust bunnies-vermin from under the bed.

    I will simply be aware of the danger. I mean I always knew that there was danger under the bed. I’ve always taken precautions.

    Being the cowardly sort I’ve never hung my feet over the side of the bed (even as a child I realized what happened to all those missing body parts on folks) and now, knowing that the dust bunnies under the bed are potentially lethal monsters like this one (even if the peril is in miniature) well –I’m glad I’ve always been circumspect about ensuring that all body parts are mummified in blankets before sleep succumbs me.

    I will avoid doing close up examinations of any dust bunnies I might vacuum up in the future.

    The horror of your blog is first the bug itself depicted in graphic details and then you give the origin of the bug. I have also found (much to my horror) that sometimes a child (one of yours) is engaged in the matter of bug collection for your posts.

    And that (going back to the earlier post) you have detailed information about how to home train a junior entomologist. This training seems to involve simply being fascinated by the bugs and infecting the child with this unwonted enthusiasm. It seems to have capsized the minds of your kids. I am shocked by Sam’s utter indifference to the vivid creepiness of the wriggly creatures –and her courage at the age of 2 in securing valuable specimens for your blog posts. She must take after you.

    The earlier blog post of the assassin bug (without its fluff and dust) was even more intimidating than I had feared. Why did I even go there? The bug with stuff on it was bad enough but now I have the vision of the naked bug to deter me from doing postponed housework that I do not want to do and now have a good reason not to do.

    Also further protective measures will have to be taken. Now I will have to put two blankets over me at night. And it is August. I will boil. But better to boil than to have such company lurking around my toes and heels.

    Yes, I am avoiding doing the Biology 20 notes.

  3. August 1, 2012

    That bug reminds me of the silicon creature in one of my favorite Star Trek episodes!

  4. August 2, 2012

    JennyW: Good question! According to this site, they have special hairs on their bodies that ooze glue, and have structures on their hind legs to help them pick up debris and toss it on their backs.

    Julie: Aren’t you glad they aren’t, say, the size of cats?

    Anne: I love that episode! One of the very few episodes of any SF show that has an alien that is really alien. Although, now that I think about it, I’m not sure I’ve ever seen it from the beginning. I may only have seen it starting at around the point where the Horta etches the words “No Kill I” into the rock with acid.

  5. Kenneth permalink
    September 5, 2014

    How do we kill them

  6. September 10, 2014

    Well, if you must, then you kill them the same way as any other insect – step on them. It’s not as if they are a big problem, though. If they are surviving in your house, then that means that there are enough other small creatures around to keep them fed, so the assassin bugs should be the least of your worries.

  7. Mario Sanchez permalink
    April 24, 2017

    I am here because I ran into one of this guys on my desk. I was working on my computer and out of the corner of my eye I thought I saw something move. When I looked it was just a large spec of dust, or so I thought. It was on top of a white page so it was clearly visible. Then it moved just a bit, and I thought it was due to the air blown from the cooling fan in the PC. But then I paid attention and I took a magnifying glass I keep near (to read very fine print) and I used a pen to push it a bit. And it started to walk!!! I have movie of it (nice for the iPhones so much at hand) I wish I could post the movie here. I live in Austin Tx. This is April 24, 2017.

  8. September 12, 2018

    love that bug x2 sm best bug

  9. Sally Vogel permalink
    August 23, 2021

    So glad to see this insect’s picture. I saw a similar one in Guyana and have been wondering what in the heck it was. The one I saw was about 22mm. long and was on tree bark heavily disguised with sawdust and frass.

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