In some species, the females emit hormones preventing the eggs from hatching out until after she dies, so that she doesn't have to compete with her own offspring for food. On one hand this is good, because you don't have to worry about the colony growing very fast. On the other hand, when you are exterminating, if you do not get the eggs out, you could create a situation where you experience very rapid hatching of thousands of eggs. If you are infected with those kinds of parasites, it is very important to follow up the extermination program with a mop plan, and eliminate the hatchlings before they have time to start mating and laying eggs. These critters carve out little pockets in the intestines, deposit their eggs, and cap them over with a mucous covering that prevents them from being eliminated. The egg shells prevent anti-parasitical herbs from killing the larva before they hatch. This is why colonic irrigation is so important, to dislodge as many eggs as possible. And mopping up any larva hatching from eggs that did not get eliminated. If you are not prepared to follow up diligently with routine maintenance, you can exacerbate a parasite problem.