UCSB Science Line
Sponge Spicules Nerve Cells Galaxy Abalone Shell Nickel Succinate X-ray Lens Lupine
UCSB Science Line
How it Works
Ask a Question
Search Topics
Our Scientists
Science Links
Contact Information
I just found a Western Corsair (Rasahus thoracicus) in my bed! It was flying around in my room, flitting up near the light. It then flew down on to my bed. I looked it up in my Insect Field Guide (Audubon) and at first I was very disturbed because it resembled a conenose bug. I read that they bite humans in the night for blood, and in fact I did have a few bug bites on my arm a couple of weeks ago which I thought might have been caused by spiders. I then searched the internet and found out that it is a western corsair because it has a very distictive orange dot on its otherwise black wings. I'm wondering if this western corsair is dangerous. I read it has a nasty bite that can be very painful. I also read that it eats other insects. But does it suck blood like the conenose bugs? Please let me know what you think. Thank you very much!!!!!
Question Date: 2006-09-04
Answer 1:

You have already done some great research. It looks like you may have found the same site I did:bugs(click here) The way I interpret this page, the western corsair does not suck blood from humans, and only bites in self defense.

While it is called an assassin bug, it belongs to a different genus than the blood-suckers (Triatoma). This means that it is not as closely related to the blood-suckers as the different blood sucking species are related to each other.

If you didn't even notice being bitten earlier, I doubt those were western corsair bites, since they are supposed to hurt as much as a sting. The painful bite does not appear to be dangerous, but if a person had an allergy or some other medical issue, perhaps it might be.

The site mentions that the blood-suckers (Triatoma) live in wood rat dens. I used to study wood rat dens in Santa Barbara County. I never got bitten by those insects. I guess I was lucky.

How do you think the mouth parts of a blood-sucking Triatoma would be different from the mouth parts of an insect predator like Rasahus?

It sounds like you'd make a great biologist. Good luck with your research on insects.

Answer 2:

UC Davis Pest Notes Publication 7455 has the following to say about Rasahus thoracicus:

"Another common assassin bug that is attracted to lights around homes, the western corsair (Rasahus thoracicus) (Fig. 2) looks somewhat similar to cone-nose bugs but has an orange and black body with an orange spot on each wing. The western corsair feedsprimarily on other insects and does not seek out warm-blooded animals or require a blood meal in order to reproduce. However, if picked up, it can inflict a bite that is quite painful."

The western corsair is not dangerous, and neither are cone-nosed bugs unless you either are especially allergic to them or in the rare case of carrying the Trypanosome cruzi protozoan. Another distinguishing feature between western corsairs and cone-nosed bugsis that the bite of a cone-nose is *not* painful(presumably because its saliva acts as ananesthetic).

Spider bites, incidentally, also cause allergic reactions.

Answer 3:

"The western corsair (rasahus thoracicus) is harmless, except for a bee-like sting. However the western cone-nose (if you're allergic) can cause the following: itching, swelling, joint pain, nausea, chills, dizziness, and anaphylactic shock. There are tropical cone-noses that carry diseases (Chagas disease, which is similar to African sleeping sickness).

The cone-noses and corsairs do not actually suck blood. The two insects are called assassin bugs, family reduviidae. Both prey on insects by using a mouth part that is sometimes called a beak, which is concealed until they attack their prey. The mouth part is used to inject a variety of enzymes to liquefy the inside of their prey. The mouth part then is used to suck up the liquefied contents of the insect. They have strong forearms to grasp their prey while they attack. Assassin bugs can be nocturnal or diurnal. While the two insects mentioned are nocturnal, the bite they deliver is sharply painful, often described as feeling like a bumble bee sting. In other words, it's painful enough that you would not be likely to sleep through it; the bites are most likely spider. The cone-nose that carries chagas disease is found in Argentina, (Triatoma insestans). In an interesting fact, Charles Darwin is reported to have contracted chagas disease in 1835 while in Western Argentina. The corsair bug is very rare."

Answer 4:

Assassin bugs are true bugs, a subgroup of the insect order Hemiptera (indeed, true bugs comprise the suborder Heteroptera). All members of this order possess a long, segmented beak originating from their mouths, which acts as a piercing stylet which they uses to pierce into something from which they feed and then subsequently suck digestible liquids from what they are feeding upon. So, for example, aphids (which are not true bugs but belong to the other suborder, Homopterous) use their beaks to pierce into plants and drink the sugar-rich water that the plant uses to carry nutrients through itself, similar to the way that we have blood.

Assassin bugs, of which the western corsair is an example, use this beak to pierce into the bodies of other insects and suck out their internal fluids, thus preying upon them; like a spider, they do not physically eat the bodies of their prey, but rather drink its juices. Cone-nosed bugs, which are a subgroup of assassin bugs, have adapted to "bite" mammals, in other words, to pierce their beaks into and suck their blood, in much the same way that a mosquito does (a mosquito is not a true bug, but a fly, which means that it belongs to the order Diptera. This is convergent evolution at work). Needless to say, even a baby human is still way too big for any insect to drink enough blood for it to be deadly; all deadly insects are dangerous either because they cause an allergic reaction (e.g. bee stings), or carry some kind of disease (e.g. malaria, West-Nile virus, sleeping sickness, etc.). Nonetheless, this is how assassin bugs kill their prey: they pierce in, suck out the insides, and then digest them.

The hairs on the insect's body are not hairs in the same way that we mammals have hair, because they are made of an entirely different material (our hair is made of keratin, a protein, and an insect's hair is made of chitin, a complex sugar). However, they are the same "hairs" as the protrusions that give bumble bees their furry appearance, or, for that matter, a tarantula its "fur" (even though a tarantula is an arachnid and not an insect).

Click Here to return to the search form.

University of California, Santa Barbara Materials Research Laboratory National Science Foundation
This program is co-sponsored by the National Science Foundation and UCSB School-University Partnerships
Copyright © 2020 The Regents of the University of California,
All Rights Reserved.
UCSB Terms of Use