Goldenrod Hooded Owlet Moth caterpillar, Cucullia asteroides, on goldenrod. (Iowa)
Geometrid moth caterpillar (Geometridae) from Monteverde, Costa Rica.
Shore fly maggot, Ephydridae (Iowa). I found this almost-microscopic larva swimming near the surface of an algae-covered pond. The breathing tubes on the posterior end (called spiracles) function like tiny snorkels, allowing the larvae to breathe underwater.
