Dim is a rhinoceros beetle who has a childlike nature, as seen when he sobs in pain after Rosie accidentally lashes one of his feet. He is also shown to be ticklish when some ant kids unintentionally tickle his thorax with their antennae while exploring beneath him. He is usually mothered by the black widow spider, Rosie. He is the largest insect of the circus troupe, and also the transport to Heimlich, Rosie, Tuck and Roll. He is big and strong but kind of cowardly like when Thud the horsefly scares his friends (although because thud maybe was even bigger than Dim).
After building the fake bird, P.T. Flea Dim's ringmaster arrives unexpectedly and reveal to the colony that the warriors that Flik brought are his missing troupe, blowing Flik's cover in the process. A distraught Atta banishes them and Flik back to where they come from. However, this was a fatal mistake to Atta, as she put herself and the entire colony in danger.
When the circus bugs perform their magic act in front of Hopper, Dim provides refuge for the Queen when she is made to look like she is put into the Chinese Cabine. After P.T. Flea accidentally aided Hopper by setting the bird on fire and Flik being beaten by Thumper Dim also helps Dot scare the evil grasshopper Thumper away. When the ants load Hopper into the circus cannon, Dim prepares to jump on it, ready to blast Hopper away, but rain begins to fall before he can do so.
As a single raindrop knocked Dim off the rock he was on, Hopper rolled right under him and he blasts him right at Flik, attempting to escape with him. He immediately grabs Heimlich and Rosie, Tuck and Roll climb onto his back and chases after them with Francis and Slim following behind, but Slim was caught in the branches, leaving Francis to find him. Rosie throws Tuck and Roll at Hopper attacking him and they manage to get his antenna and Hopper manages to trap them between branches. But Atta intervenes, rescues Flik and they lead Hopper into the real bird. The enraged Hopper mistook the bird for fake and taunts it and only to be fed to its chicks putting his reign of terror and insult on the ant colony and circus bugs to an end.
At the end of the film, some of the Blueberries try to hide under Dim's wings, but Rosie spots them. As the circus troupe leaves the island, Dim carries the wagon, leaving Heimlich to be carried by Manny and Francis instead.
- Dim was Brad Garrett's first Pixar character.
- Out of all the circus bugs, Dim seems to have the least number of lines throughout the film.
- Toys of Dim and his friends can be seen at Al's Toy Barn in Toy Story 2.
- When Dim hides the Queen under his wings, Manny mistakenly calls him a dung beetle, when he is really a rhinoceros beetle, though rhinoceros beetles are a subfamily of the scarab beetle (dung beetle) family.
- When Dim roars to help Dot scare Thumper away, his roar sounds just like the T-Rex in Jurassic Park, a similar way to how Rex roared in Toy Story 3.
- Dim also provided the same roars from the T-Rexes in The Lost World: Jurassic Park.
- Dim's horn structure wasn't meant to be reflective of a specific kind of horned beetle. However, in 2006, entomologist Brett C. Ratcliffe discovered a species of rhinoceros beetle that closely resembled Dim which was named Megaceras briansaltini and dubbed the "Nature imitates art" coincidence as The Dim Effect.