“Chomp, chomp, chomp, anal scrape. Chomp, chomp, chomp, anal scrape.” That, National Geographic reports, is the sound of the masked birch caterpillar’s social life. These future moths form groups to make their silken protective shelters, and they need a way to recruit new friends to the building effort. Their solution? Scraping their anal hairs against leaves in complex patterns. Presenting last week at the International Congress for Neuroethology, researchers said that the caterpillars are more likely to “talk” like this when other caterpillars are crawling nearby. And the louder and more intricate these scrapes, the more likely other caterpillars will join their building effort.