Understanding Flea Lifecycles for Household Prevention and Treatment

Fleas have a multi-stage lifecycle. The female flea lays eggs, which hatch, grow, and then form a cocoon. This cocoon stage is what makes fleas so difficult to get rid of. The cocoon is impenetrable to pesticides and can stay in a dormant state for up to two years. The cocoons come to life again as the weather turns warm and moist and vibrations are sensed from nearby footfalls. As the cocoons awaken, new fleas are hatched and the lifecycle begins again. In an active period, the full lifecycle from egg laying to the hatching of new fleas takes about 2 weeks. From this knowledge we begin our fight against the fleas.

Flea control needs to be a two-pronged effort and both the outdoors and indoors need treated. Fleas from the yard can hitch a ride on pants, socks and shoes to infiltrate interior spaces. Taking the extra step to treat the yard will help with the interior treatment.

The first aspect of flea control is to kill any existing fleas. I recommend staying away from the harsher chemicals such as Dursban and Diazinon. Pyrethrin based insecticides are the best to use as they are effective at killing bugs, but they do relatively little harm to humans and the environment. Pyrethrin is derived from the hibiscus flower. It is relatively unstable and tends to break down a bit too quickly, so the newer derivatives ending in -methrin (resmethrin, tetramethrin, etc) which are more stable in UV light are the best. Spray down soft surfaces inside and the yard outside. Repeat this step in two weeks.

The second aspect of flea control is to prevent new fleas. Once again, you will want to treat the exterior and interior of your home. You will need to find a product that is an Insect Growth Regulator (IGR). The IGR works by interrupting the flea's lifecycle and preventing the flea from ever reaching adulthood. This will stop additional flea eggs from being laid and reduce the number of biting insects. The IGR should be reapplied both inside and out, every 6 months for 2 years.

If the home has a current infestation, keep applying the insecticide in two week intervals until a drastic decline in the number of fleas is seen. Once the problem is under control, treating every 6 months to a year will be sufficient. If the goal is prevention only, then the insecticide and the IGR should be applied once a year in the spring.