Some evolutionarily younger caterpillars use their butts to warn off others. "To defend their territory and keep out intruders, the larvae can wear one of at least two hats: tough-guy bully or sophisticated orator. The former lets an intruder know who's boss with aggressive maneuvering, crawling up to the enemy, pushing and biting to try to evict it from a leaf. The civilized talker instead scrapes its rear on the leaf, sending out vibration signals saying the equivalent of 'You better leave now, or else.' These more posh caterpillars also use their mouth parts to drum on the leaf and scrape across the leaf's surface."
"'We conclude that the anal scraping movement is a modified component of crawling, and that instead of moving forward, D. arcuata walks on the spot, to talk,' lead author Jaclyn Scott of Carleton University and colleagues write in the April 12 issue of the journal Nature Communications." [Oh, caterpillars also moon walk! Sweet!]
"Another idea is that the vibrations from the scraping and drumming are so loud they attract birds on the hunt for meaty insects. And the resident has a little silken shelter and might be telling the intruder, 'I'm making a racket here so if you want to take cover you better take off.'"
Full article here.
Happy Earth Day!