A Bug's Life is a platform game with different goals in each of 15 levels. Most of the goals deal with getting the main character, Flik, to do events that match the storyline of the movie. When the player finishes a level, that player can proceed to the next level. Each new level starts with a new short animation from the movie. If the player collects all of the bonus items in a level, that player gets a bonus movie. Bonus items include 50 pieces of grain, four letters that spell F-L-I-K (similar to the Nintendo 64 and PlayStation versions of Disney's Tarzan) and permanently finishing off each enemy bug. Floating telescopes guide the player through each level.
Throughout each level are a variety of seeds. Some seeds are partially buried in the ground. These seeds can be transformed by Flik into a specific kind of plant that can help him solve problems within the levels. Flik can increase the number of plants he can grow by collecting colored tokens scattered throughout the levels, with a token's color determining what type of plant can be grown with it.
Obtainable throughout all the levels are a series of berries which can be thrown at enemies to kill them. How long the enemies stay dead, once hit, depends on the kind of berry Flik throws at it. The player starts out each level with the red berry. There are only two ways to collect the super berry, homing berry, mega homing berry, and gold berry: (1) by finding the actual berry somewhere in the level or (2) collecting purple tokens, turning a seed purple, cracking it open, and obtaining the resulting berry that way. One purple token is required to obtain a super berry from seed, two purple tokens to obtain a homing berry, three purple tokens to obtain a mega homing berry, and four purple tokens to obtain a gold berry. Some levels do not contain certain berries; the only way to get those berries is to collect enough purple tokens to get that berry from a seed.
Flik's grain machine is present in certain levels. If the player finds the machine and puts it on, it will destroy any enemy that comes into contact with it. The machine is also handy in collecting grain at distant ranges. When Flik is in the machine, he cannot jump.
Several bosses are encountered during the game: