Viceroy (butterfly)
The caterpillar feeds on trees in the willow family Salicaceae, including willows (Salix), and poplars and cottonwoods (Populus). The caterpillars store the salicylic acid in their bodies, which makes them bitter, and upsets predators' stomachs. As further protection, the caterpillars, as well as their chrysalis stage, resemble bird droppings.