110 days to go to Insect Week
(Ancient Greek - pleco = folded or braided ; pteron = wing)
Aquatic insects that live in running water as larvae.
There are lots of contenders here – possibly the pretty red and blue rove beetle Paederus – very, very tiny amounts of its poison have been used to cure chronic ulceration in people. Ladybirds are pretty poisonous (and pretty) and can bleed foul-tasting poisonous brightly coloured blood from their knees.