Fleas have a complex lifecycle that includes eggs, larvae, pupae, and adult stages. While adult fleas live on hosts like pets, the majority of the population—eggs, larvae, and pupae—develop in the surrounding environment. This is why infestations often persist even after visible fleas are treated. 

Fleas can reproduce quickly, with a single female capable of laying dozens of eggs per day. These eggs fall off the host and settle into carpets, furniture, and other surfaces, where they continue developing. Under the right conditions, populations can grow rapidly and spread throughout a home or property. Homeowners may notice pets scratching excessively, small bites on ankles or legs, or tiny dark specks (flea dirt) on surfaces or pet fur. Fleas may also be seen jumping on carpets or furniture.  

In addition to causing irritation and discomfort, flea bites can lead to allergic reactions in pets and humans. In some cases, fleas can transmit parasites such as tapeworms to pets. Because much of the infestation exists in hidden life stages, effective flea control requires addressing both the host (pets) and the environment to fully eliminate the problem and prevent reinfestation.