Flea eggs do not go dormant. It’s sometimes stated that flea eggs can enter into a state of dormancy when facing poor environmental conditions, such as during winter. These sources are largely uncited websites and books, and the information is inaccurate. Flea eggs die when they’re exposed to unfavorable conditions.
Flea Eggs don’t go Dormant
Flea eggs don’t go dormant in unfavorable conditions. They die. The eggs are vulnerable to fluctuations in ambient temperate and relative humidity. For instance, flea eggs perish outdoors during winter due to the dry, cold air.
Ambient temperature regulates how quickly flea eggs develop. As temperature is lowered, the eggs take longer to hatch. In poor conditions, it can take 8-12 days. The eggs die once temperatures drop blow 55.4°F (13°C). At the other extreme, 100.4°F (38°C) is lethal to flea eggs. Flea eggs desiccate and die in arid environments. A relative humidity below 50% is lethal.
Cocooned Adults can go Dormant
Fleas can enter a dormant-like state. However, this is only done following pupation. Inside its cocoon, an adult flea can remain in a quiescent state until a suitable host is detected nearby. This life stage is called the pre-emerged (pharate) adult. The so-called pupal window can last for up 155 days before the adult flea emerges.