In addition to mimicking each other and surrounding foliage, some insects (like this caterpillar from Belize) have evolved to mimic bird droppings, a phenomenon known as mimesis.
Saturniid moth caterpillar, Automeris sp., from Belize.
Flannel Moth caterpillar, genus Megalopyge, from Belize. These larvae sport venomous spines that can cause a painful sting and inflammation, and sometimes other unpleasant sensations like headache and nausea.
