A species of European butterfly has an excellent trick for protecting itself during a vulnerable stage of life. As the caterpillars prepare to enter their inactive pupal stage they emit ant-like chemicals that cause red ants to scoop them up and bring them inside the ant colony. Then, to get star treatment, the caterpillars make a rhythmic noise that resembles the call of the ant queen. That's enough to get the worker ants' undivided attention, a new study shows.