Egg sacs appear as light green spheres with some legs sticking out at the bottom of the sac. Egg sacs contain bunches of small black spiders inside of them, which is revealed when the player swats the sacks using the flyswatter.
Egg sacs appear only on stage 2.5, placed in the middle of the screen. The player can break them by swatting them, this causing some spiders to be released out. The spiders, upon being released, will try to escape by running in several directions at a high speed. The player must be fast to swat them. Each egg sac has 15 baby spiders inside it.