The Crumbug is an enemy found in Hey! Pikmin. It is the first and the most basic enemy you will encounter. It resembles a little square-shaped piece of bread. Its only attack is walking and it doesn't stop before cliffs.
Hey! Pikmin Creature Log
"Its only move is to walk straight toward you without stopping. Is that so it can eat us or we can eat it?"
Crumbugs will die after one Pikmin is thrown at it, but be careful to throw the Pikmin far enough, otherwise it could fall just in front of the Crumbug's mouth and die. They will stop for a few seconds after eating a Pikmin or damaging Olimar. This gives you a chance to attack it.