Flea Dirt

- A sure sign of a flea infestation -

Summary: Flea dirt is simply dried blood and feces excreted by fleas. It accumulates in the fur of an infested animal or in the animal's bedding. If you find flea dirt during regular combing it is a sure sign of a flea infestation.

Jack DeAngelis, PhD

OSU Ext. Entomologist (ret.)

Flea dirt is a sure sign of fleas

Flea dirt is made of bits of dried blood and feces excreted by feeding fleas and it looks like large, dark-colored dandruff in the pet's fur. Flea dirt accumulates in the fur and bedding of a flea-infested animal and its presence is a sure sign of a flea infestation. If you are not sure whether or not you have found real flea dirt, drop the bits into water. If the bits dissolve, turning the water red, it's flea dirt.

Flea larvae, living in the animal's bedding, actually feed on these bits of dry, excreted blood. The more fleas you have the more that flea dirt accumulates so the amount you uncover is a pretty good indication of the severity of the infestation. Small, easily managed infestations are often detected during regular combing when flea dirt attaches to the groomer's flea comb.

Flea control

The following is only a brief summary of our suggestions for flea control, for a more complete discussion of our recommendations see Flea Control in Homes and on Pets.

Step 1: Brush or comb the infested animal frequently to remove adult fleas and look for flea dirt. At least once a month shampoo your pet using a good quality flea & tick shampoo to kill the adult fleas that bite.

Step 2: Treat pet bedding areas with a spray containing the insect growth regulator methoprene. Methoprene prevents immature fleas from developing into adults (see Using Methoprene For Flea Control for details). This will effectively stop the infestation but won't kill adult fleas (see Step 3).

Step 3: To kill adult fleas treat animals with a topically-applied flea medication like Frontline Top Spot or Advantage, or use a flea shampoo weekly, along with daily combing, until no more fleas or flea dirt are found.

Life Cycle of Fleas

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