Those who hunt by night will tell you that the wildest, most vicious of all animals is the tiny shrew.
The shrew feeds only by the dark of night. He must eat his own body weight every few hours or stave to death. The ravenous shrew eats everything, bones, flesh, marrow… everything.
Intro from Attack of the Killer Shrews 1959
These little beetles have heads at both ends of their bodies. This allows them to feed on leaves at twice the rate of their normal cousins, causing great damage to crops. They look like ladybugs more than actual beetles, but have no wings. They have a funny way of moving if one stops to watch them, as both heads seem to vie for picking the direction at any given time. Their favorite nourishment is sugar cane. After feasting on these for some time, they develop short bursts of frenetic energy, and can be seen racing back and forth without purpose, which looks quite comical to onlookers. They are otherwise normal bugs. Of course the pc's might not know that.