Heimlich is a green caterpillar with a German accent, and he works as a clown in P.T. Flea's circus troupe. He is very gluttonous and always seems to be eating. Even during a performance, he offered to help finish one of the audience's candy corn. The fly refused, but then it turned out that he got the candy corn anyway. He then later calls the flies "Poo Poo Heads," when Francis is arguing with them. At the beginning of the film, he says that he dreams of being a beautiful butterfly. He also at one point turns gray when he sees the mural of his being killed. At the end of the film, he sprouts a pair of tiny wings, but really is still a caterpillar (due to his obesity), having only turned blue, and it takes the efforts of Francis, Manny, Flik, and a few other ants to get him up in the air. Whilst a caterpillar, Heimlich was carried by the rhinoceros beetle, Dim, for transport.