Science Wednesday: The “Kissing Bugs”

by Katie Bowell, Curator of Interpretation

Since it’s close to Valentine’s Day, I thought it would be appropriate to talk about one of my favorite groups of insects: the “kissing bugs.”

What are the “kissing bugs?” Large, predatory insects.

You wouldn’t think they were predators to look at them – with their long, bent mouthparts and lumbering gait, these bugs seem more like miniature elephants than killers, but killers (or at least blood suckers) they are.

Kissing bugs belong to the insect family Reduviidae, and Reduviids are famous for using their long, elephant-esque mouthparts to inject lethal saliva into their prey.  The saliva liquifies their meal from the inside out, and the insects then use their mouthparts to suck up the liquid goo. If you’ve ever come to the museum’s “Meet the Animals” program, you may have seen some Reduviid insects: our Assassin Bugs.

Two-spotted Assassin bugs

So what does this have to do with kissing?

One group of the Reduviid insects are the kissing bugs.

Kissing bugs don’t liquefy their prey; they feed on their blood, instead. Kissing bugs bite people at night, creeping out from cracks in the walls and floor to crawl over people as they sleep. Because kissing bugs are attracted to the carbon dioxide we exhale, they often bite around the mouth, nose and cheeks – where a nicer animal would only give us a kiss.

If all the kissing bugs did was bite the occasional sleeper, it would be itchy and annoying, but not that big a deal. But kissing bugs do more than just kiss…erm…bite: in Mexico, Central and South America they can transmit Chagas Disease.

Every time kissing bugs come out at night to feed, they also poop. In order to fill their bodies with blood, they have to empty out all their waste. Often, along with defecating regular frass (what you call “poop” when you’re an insect), kissing bugs also expel the tiny Trypanosoma cruzi, which is the cause of Chagas Disease. If T. cruzi enters the bitee’s bloodstream, the parasites multiply in the blood and then infect organs throughout the body. Left untreated, the disease can damage the nervous system, digestive system and heart, and can be fatal.

Trypanosoma cruzi

 

Trypanosoma cruzi in the blood

Along with having a romantic name (if not a romantic reality), there’s another reason talking about kissing bugs in February is appropriate. While it’s never been proven, many people suspect that Charles Darwin, whose birthday is this Saturday, died of complications from Chagas Disease. In Darwin’s The Voyage of the Beagle, he writes

At night I experienced an attack (for it deserves no less a name) of the Benchuca, a species of Reduvius, the great black bug of the Pampas. It is most disgusting to feel soft wingless insects, about an inch long, crawling over one’s body. Before sucking they are quite thin, but afterwards they become round and bloated with blood, and in this state are easily crushed. One which I caught at Iquique, (for they are found in Chile and Peru,) was very empty. When placed on a table, and though surrounded by people, if a finger was presented, the bold insect would immediately protrude its sucker, make a charge, and if allowed, draw blood. No pain was caused by the wound. It was curious to watch its body during the act of sucking, as in less than ten minutes it changed from being as flat as a wafer to a globular form. This one feast, for which the benchuca was indebted to one of the officers, kept it fat during four whole months; but, after the first fortnight, it was quite ready to have another suck.”

So this Valentine’s Day, feel free to spread the kisses around, but try to avoid any insects that want to “kiss” you back!

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February 2011
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