Slim is a pessimistic walking stick who acts as a clown in P.T. Flea's circus troupe. It appears that he is unhappy with his position at the circus troupe, as his boss constantly casts him as a prop instead of a character, with such castings as a broom, a pole, a stick and a splinter. He is the tallest insect in the troupe and is shown to be best friends with Heimlich and Francis, often treating other bugs with more respect in contrast to Francis' aggressive nature. However, he seems to tolerate it, as seen when he calmly broke up a fight between Francis and a couple of flies during a performance. Unlike most male walking stick, Slim does not have wings and cannot fly. Because of this, Francis usually carries him for transport. At one point, Francis, while chasing after Hopper who kidnapped Flik in retribution for the ant rebellion, accidentally loses Slim in a branch group. At the end of the film, when the Circus Bugs leave Ant Island, Slim rides on the back of the circus wagon since Francis helps Manny carry Heimlich.