|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
|Question Date: 2006-09-04|
You have already done some great research. It
looks like you may have found the same site I
here) The way I interpret this page, the
western corsair does not suck blood from humans,
and only bites in self defense.
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.
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?
like you'd make a great biologist. Good luck with
your research on insects.
UC Davis Pest Notes Publication 7455 has the
following to say about Rasahus
"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."
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).
incidentally, also cause allergic reactions.
"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
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."
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).
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