Maggots simply crawl around the room blindly in cardinal directions, not targeting Isaac. Because they don't follow Isaac and move very slowly, it is easy to avoid them. Maggots are thus only dangerous in great numbers and enclosed areas, where it can be difficult shooting at them safely without running into them.
Chargers are a more advanced form of Maggot, and they're encountered more often as well, present on The Caves, The Catacombs and The Depths. They possess a smiling face of sorts, and look quite harmless as they slowly crawl along without attempting to follow Isaac. However, once they are directly aligned with Isaac, they will open their mouth, revealing a row of sharp, pointed teeth and charge in a straight line, their speed greatly increasing during this charge. Because they're always encountered in groups of at least four, avoiding them quickly becomes a problem.
Chargers can be spawned by Chub, Sloth, Pestilence and Fistula (only upon destruction of smallest parts). They are also spawned upon destruction of the Green Champion version of The Hollow's body segments.
Spities are much fatter than other maggot forms, and also possess a face like Chargers, and have the same health as them. Instead of rapidly attacking the player in their line of sight, however, they will simply spit out a shot ahead of them while crawling along slowly. They have good range but slow firing rate, and because they're not aimed at anything, the player is very unlikely to get hit.
- Sometimes, Chargers get stuck in gaps until Isaac comes too close and lets them charge.
- If the player avoids moving once entering a new room, the Chargers may not perform their charge even if they get a clear line-of-sight.
- Spities can sometimes shoot at opposite site than the on they're facing (i.e. They look away from Isaac but still shoot at him).
- Maggots tend to get stuck in open doors.