In A Bug's Life, the chubby caterpillar who dreams of becoming a butterfly is Heimlich. He is one of the Circus Bugs who are mistakenly recruited by Flik to defend Ant Island from Hopper's grasshopper gang.
Heimlich is cheerful, hungry, and distinctly German-accented. His repeated wish to become a beautiful butterfly is played for comedy because he remains a caterpillar throughout the film. During the climactic battle, however, he briefly emerges from his cocoon with tiny wings before reverting to his familiar form.
The character was voiced by Joe Ranft, a Pixar story artist who helped shape many of the studio's early films. Ranft's scratch vocal performance was heard by Nancy Lasseter, who suggested that he play Heimlich. The voice became one of the film's most recognizable comic performances.
Heimlich is easy to confuse with Flik, the inventive ant protagonist, or Dot, the young princess. P.T. Flea is another member of the circus troupe, but he is its fiery ringmaster rather than the caterpillar.