The life cycle of a tapeworm starts with a human eating undercooked, infected meat. The tapeworm will then grow and release small packages of fertilized eggs and sperm. These packages are excreted by the host. If they happen to land in grass, for instance, the package will open. By that time, the tape worm eggs will have developed. The eggs are released onto the grass. If a cow were to eat that grass, the eggs would become larvae and burrow into the cow's muscle. If that cow was eaten without being cooked thoroughly, the whole cycle would start again.