What Is Flea Dirt? Color, Shape, and Size

What is flea dirt? Flea dirt (flea poop or flea frass) is the round black pepper or dandruff-looking specs made up of undigested and dried blood (dropped by fleas) after sucking blood from cats, dogs, or humans.

You can find flea dirt when combing or running fingers against the grain of your cat’s or dog’s hair. Flea dirt is mainly found around your cat’s or dog’s groin area, the tails, or between their hind legs.

Ultimately, flea larvae will feed on the flea dirt – remember its blood anyway. But most fleas must be controlled from their hiding places in the house or the yard

What Is Flea Dirt? Flea Dirt’s Color, Shape, and Size 

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Fleas will poop either in their hiding place or on cats and dogs. The dried-up blood (in the form of excreta) will produce oddly-shaped black, brown, or reddish specs – which we now referer to as flea dirt. Most homeowners confuse flea dirt (a collection of the flea poop) with black dandruff. 

The flea dirt will look like (1) Specks of grit or Ground pepper, (2) Black dandruff or Tiny black flakes, (3) Black or reddish specks.

Coils or Spherules 

Flea poop mainly takes two shapes – Coils or Spherules. First, coils will be about 0.84 mm in length – and thus, their largest mostly go lengthwise. 

But, the Spherules will mainly grow into a round shape of about 0.08 mm to 0.24 mm. The flea adults will first take the form of spherules but turn into coils in their next two weeks. 

How to Check for flea dirt/ flea dirt test? 

It’s easy to stop fleas and flea dirt on the belly of either your cat or dog. The stomach mainly has the fur or hair that is less thick and has the lightest shade of color. Also, you may find flea dirt on your dog’s or cat’s sleeping areas and bedding.

If you’ve found flea dirt on your pest, then this could be a good indicator that you’ve succeeded in identifying the presence of fleas. Further, the specs will turn your wet towel into spots of red or brown.

1. But, you can easily discern flea dirt by placing any of the black specs or clumps on a white and wet towel.

2. If the towel becomes reddish or brown, then that points to the presence of flea dirt – which, as noted earlier, is merely undigested blood in flea poop.

3. Also, check the pet’s sleeping areas and bedding

Why worry about Flea Dirt?

1. Fleas will suck about 5 µl to 6.97 µl of blood each day to fill up their gut. However, female fleas will suck an event larger blood capacity (13.6 µl of blood).

Therefore, controlling flea dirt (and fleas too) would ensure that you reduce the amount of blood sucked from cats, dogs, or human beings

2. Flea dirt is “dirty” on your pets and humans as it leaves the feces to spread all over. For example, fleas will excrete about 8-10 feces drops in their 2-3 minutes of feeding.

Each day, an adult will drop feces with a weight of about 0.636-0.860 mg (with female females excreting more wastes – about 0.8473 mg). 

3. Fleas find it less energy-consuming to feed on the pet and human blood. Fleas are generally considered to be capillary (vessel ) feeders – which allows faster feeding.

Vessel feeding implies that the bugs will take advantage of the pet’s blood pressure and thus take in the blood faster. Further, the bugs have anticoagulant saliva and adequately adapted mouthparts for better blood sucking – and losing a limited amount of energy. 

4. Flea dirt is not just waste for the flea but will also feed flea larvae and promote the development of a major flea infestation. But why? Flea dirt is appropriate to flea larvae as it requires them to spend a very minimal amount of energy. 

It provides flea larvae with proteins and iron that are required for sclerotization and body development. Therefore, that’s why females take more massive blood amounts to feed their larvae -with proteins, iron, and even vitamin B. 

How to Get Rid of Flea Dirt?

Well, besides killing the fleas, you’d love to get rid of the flea dirt. The simple steps are shampooing your dog and cats to wash away the flea dirt.

But this is no guarantee that the flea dist won’t come back to haunt you. But, the best way to rid your pets of this flea dirt is by killing the fleas both in and around the house.

For your cats and dogs, I would recommend using various flea treatment methods such as Capstar Flea Killer, oral pills, Frontline for the cats, or Advantage II for your Dogs. 


  1. NCBI – Comparison of Two Techniques for the Detection of Flea Faeces.
  2. PetMed – Flea Dirt How to Get Rid of It
  3. Comparison of Two Techniques for the Detection of Flea Faeces in Canine and Feline Coat Brushings

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