Internal parasites, regardless of genus or host animal, generally follow the same life cycle. Inside an animal, the adults produce eggs, which are passed out of the animal. Given the right conditions, the eggs hatch into larvae, which wriggle out of the manure pat and up a blade of nearby grass. There, they wait for an animal to ingest them. Once inside a new host, the larvae become adults, and the process starts over again. Worm management is a tricky process, but luckily there are some really effective products available to help you beat the cycle.