Flea cocoons don’t drown easily in water. When submerged for 12 hours, 62% of cocooned fleas will survive. However, 100% will die if they’re in water for a week. The cocoon itself isn’t a water barrier.
How Long it Takes Flea Cocoons to Drown
Cocooned flea stages are least affected by environmental conditions, including flooding. In an experiment with dog fleas (C. canis), the cocoons easily withstood being soaked in water for 12 hours. However, they were destroyed after a week of being submerged Fig 1. The cocoon’s structure can vary and may slightly affect how it reacts to water. Sand, dust, and other particles absorb water differently.
Fig 1 Percent of cocoons (y-axis) which survive after submerged in water for various durations (x-axis).
Cocoons aren’t a Barrier to Water
Not a Water Barrier
Flea cocoons don’t create a water barrier. They aren’t air or water tight. Humidity is similar inside and outside cocoons. As such, the silk structure doesn’t protect fleas from water loss or desiccation. However, compared to other life stages, cocooned fleas can survive longer in low humidity. This is because they’re in a resting state and their metabolism is slowed, so they’ll lose less water from respiration.
Not an Insecticide Barrier
Insecticidal sprays don’t have much affect on cocooned fleas. The cocoon may absorb the insecticides. which could be detrimental. However, the chemicals may cause fleas to emerge, but they’ll rarely kill them. The cocoons aren’t a barrier to chemicals. Rather, the fleas develop within carpeting and the canopy protects them from the sprays.
Purpose of Cocoons
The primary function of the cocoons is to provide physical protection and to camouflage the fleas. Without a cocoon, other flea larvae may consume the pupating flea. They also allow adult fleas to postpone emergence and prevent fleas from detecting non-host stimuli.