We recently received a new friend from Texas – nicknamed “Joe Acronicta” by the collaborator who sent him to us.
This is one of my favorite species – Acronicta atristrigatus, also known as the “Paddlemaster”. I bet you can guess why.
What we’re all wondering, though, is what those paddles are for. They appear on several Acronicta species, but in different arrangements. Some only have them in place of the dorsal setae, while others are nearly covered in paddles. I have a feeling they are used to thwart parasitoids which may try to land on the caterpillar to lay their eggs. Many species of flies and wasps see caterpillars as big tasty meals for their offspring.
I imagine all those hairs would make it difficult for a parasitoid to land. And if it does, the caterpillar will surely notice.
These guys also have some interesting defensive behaviors.
Don’t worry, I did not hurt the caterpillar! Like most Acronicta species, it starts with a bite (or attempted bite). But instead of simply returning to its perch, the caterpillar begins to sway side to side. We are all curious as to whether this serves to deter birds, or parasitoids, or perhaps the caterpillar is trying to sway gently like a tree branch?
What do you think?