Img 1 Cat fleas don’t drown quickly because they don’t break the surface tension of water.
Fleas can survive for up to 7 days when dropped in water. When submerged, it takes fleas at least 24 hours to drown. Adding a couple drops of dish soap to the water will speed up the process. Dish soaps contain surfactants, which reduce water’s surface tension and cause fleas to sink and drown.
Insect respiratory systems are resistant to oxygen deprivation. Insects won’t drown when submerged in water for only a few hours. As far back as 200 A.D., Claudius Aelianus reported that flies couldn’t be easily drowned.
Drowning Fleas in Water
How Long it Takes Fleas to Drown
Fleas can survive up to 24 hours while submerged in water. They can be revived if they’re removed up this point. When fleas are placed in water, not submerged, they’re nearly impossible to drown. In one study, seven squirrel fleas were dropped in water. Only one died within 24 hours. The others lived up to seven days.
Why Fleas don’t Drown Easily
Fleas, and other insects, have wax-covered cuticles. The outer waxy layer repels water and makes them non-wettable. The oil-like coating also helps fleas slide through host hair. It’s likely that the cuticle wax extends into the trachea and prevents water from entering the respiratory system.
Fleas don’t break the surface tension of water due to their water-repellent cuticle and small size Img 1. In natural settings, they’ll remain on the water’s surface, flailing around and possibly crawling out. Rubbing petroleum jelly on the water container’s rim can help prevent escape.
Surfactants & Soapy Water
Using soapy water as an insecticide dates back hundreds of years. Today, fleas are commonly drowned by adding dish soap to water. Examples: (1) Making a flea trap by placing a plate of soapy water beneath a lamp. (2) Drowning fleas in a bowl of soap-water as they’re combed off of a cat.
Making Fleas Sink
Dishwashing liquids, such as Dawn, contain surfactants which lower the surface tension of water. It only takes a couple drops of detergent to reduce the water’s surface tension enough for fleas to sink and drown.
Dawn dish detergent is most commonly used for flea control. However, Jet-Dry is a more concentrated surfactant and doesn’t foam. It may a better option if fleas are jumping out of the water by climbing onto soap bubbles and suds.
Counteracting Cuticle Wax
The surfactant properties of dish soap also make insects more wettable. The once hydrophobic waxy cuticle will no longer repel water. As a result, water can enter into their spiracles and respiratory systems, displacing air and drowning the insects. Additionally, sudsy water may physically block the spiracles, preventing the exchange of air and causing suffocation.
It’s theorized that soaps work as insecticides by breaking down cell membranes and by removing cuticle wax. As a result, insects can’t retain water and they rapidly desiccate. Soaps may also act as growth regulators, interfering with the cellular metabolism of insects.
Experiments done with glycerine soaps have shown little to no effect on fleas. It takes up to four days for fleas to die in 50% glycerine and 50% water.
Bathing Pets with Dish Soap
Dish liquids are sometimes used as alternatives to flea shampoos for pets. However, dish soap isn’t made for animals. It’s much harsher than pet shampoos and will remove the protective oils from an animal’s haircoat. As a result, their skin can get extremely dry and irritated. Even with the more gentle, pH balanced shampoos, it’s recommended not to bathe pets more than once a month. Avoid using dish soap on pets with skin infections.
Drowning Fleas in Vegetable Oil
Homemade flea traps sometimes use vegetable oil to drown fleas. Vegetable oil has around half the surface tension of water. It’s also more viscous. Fleas jumping into oil will quickly get trapped and sink, eventually drowning or suffocating.
Washing Machines & Dryers
Most flea control programs recommend frequently washing animal bedding and rugs. When laundering these items, run the washing machine at 140°F for ten minutes. Then use the highest heat setting on the dryer.