As bugs go, crickets are pretty harmless. Loveable, even.
Except, maybe, for African armoured ground crickets. When attacked, these little buggers vomit and squirt toxic blood through crevices on their backs and under their legs.
Scientists have known about the bleeding and vomiting for a long time. And they've known in a general way that these are defense mechanisms for crickets and several other kinds of insects, including many beetles. But scientists didn't know exactly what triggers the bleeding and vomiting, or how well it works to deter predators.
Australian researchers seem to have figured it out by attacking ground crickets with tweezers. When grabbed from the side, the crickets chirped and tried to bite. They also sometimes squirted blood--which is pale green and has a sharp, bitter smell, by the way.
But when the crickets were grabbed from above and couldn't bite, then the green, smelly blood really started to flow. The insects also threw up their most recent meal.
Does This Work?
So how well do bleeding and vomiting work to fend off predators? Pretty well.
The researchers put some crickets in a cage with hungry bearded dragon lizards. As soon as the lizards attacked, the crickets oozed blood and vomited. One lizard with a bleeding cricket in its mouth dropped it and backed off.
Other lizards didn't even bother trying.
One problem, though, is that crickets are prone to cannibalism. So while bleeding and vomiting may help fend off outside predators, a cricket covered in its own blood and guts is in danger of getting eaten by its own kind.