What color are fleas?

adult cat flea with no wings

Tom Murray

Img 1 Adult cat fleas (Ctenocephalides felis) have dark brown-red colored bodies. The cuticle has glossy surface.


Adult fleas are a dark brown color. Their color is also sometimes described as light brown, reddish-brown, or black.



Adult cat flea bodies are dark brown. They may sometimes appear as light brown, reddish-brown, or black.

Newly emerged adults typically have a darker color, and may appear almost black. This is because unfed fleas have overlapping abdominal segments. Upon consuming a blood meal, their abdomens expand and double in size. After feeding, the segments are spread out and no longer overlap. As a result, their bodies appear a lighter brown color.

Glossy Sheen

Fleas have a glossy appearance. The frontal region of a flea’s body has numerous pores. These pores are epidermal glands which release an oily substance onto the surface of the flea to help facilitate movement through a host’s hair.


Cat fleas possess rows of large, black spines located on their head and thorax. These are called ctenidia or combs. These dark spines are hardened and heavily sclerotised outgrowths of cuticle rather than normal bristles (setae). A genal comb is located on each side of a flea’s head, with each comb containing 7 to 8 spines. The pronotal comb is found on the posterior border of the first thoracic segment. It has 7 to 9 spines on each side (totaling around 16).


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  • A Kirkman January 2, 2018, 10:42 am

    It’s not exactly “unrelated”. I am wondering how many “heads” does a flea have? The article says “on each of a flea’s head’s” and not “on each flea’s head”. Am I nitpicking? – no (unrelated) pun intended – I am not an entomologist, so obviously I didn’t understand all of the article. I just find it very interesting what I have learned about my cats’ fleas here on fleascience.com, and had that question. Thank you.

    • Adam Retzer January 2, 2018, 12:02 pm

      That was a typo. Thank you for pointing it out. It should read: “A genal comb is located on each side of a flea’s head, with each comb containing 7 to 8 spines.”