Flea Bites

flea bites

Michael Voelker

Img 1 Flea bites appear as papules, often in clusters of three. View more pictures.

This page provides a quick summary of flea bites, in the form of a FAQ. Click on the answers for detailed information, including citations.

What do flea bites look like?
Flea bites initially appear as elevated skin, but later develop into hard bumps, which have diameters of 1-3 mm. Redness often surrounds the bites.

Do flea bites appear in groups?
Yes, often groups of 3. Fleas probe the skin multiple times for a good feeding location. They may also get disturbed while feeding, causing them to seek a new nearby location.

Can flea bites blister?
Yes. But it isn’t the common reaction.

Can flea bites swell?
Yes. Swelling (edema) can accompany flea bites.

Do flea bites have pus in them?
No. But secondary infections can develop if the bites are scratched. The infections can result in pus-filled lesions.

Do flea bites scar?
Not usually, unless they’re picked at or scratched.

Do flea bites hurt?
No. People may not even realize they’ve been bitten until an itchy reaction develops a day later.

Do flea bites show up right away?
The skin elevates (wheals) shortly after the bite but it isn’t very irritating. The wheal fades in 12-24 hours and is replaced by an itchy welt (papule).

How long do flea bites last?
Flea bites begin fading 48-72 hours after the bite. They’re usually gone within a week. Scratching the bites can delay the healing time.

Where do flea bite people?
Most often the ankles and lower legs. This is the height fleas can jump to, and they feed upon reaching exposed skin.

How do fleas feed?
Fleas are vessel feeders, exploiting blood pressure for rapid feeding. Their mouths consists of 3 needle-like stylets. The outer two pierce the skin, and the center stylet enters the capillary to draw blood. Anticoagulant saliva drips to the wound to help facilitate the process. Feedings last around 10 minutes.

Do male fleas bite?
Yes. Both sexes rely exclusively on blood for sustenance.

How much blood do fleas consume?
Fleas drink around 6.97 ul of blood per day. Females consume more than males, up to 13.6 ul of blood daily, which is over 15 times their body weight. The excess blood is excreted as feces, which feeds the larvae.

Why do flea bites itch?
Itching is caused by flea saliva, which contains antigens that trigger various immune responses. The itchiness causes pets to scratch themselves, which helps disperse eggs and flea feces (larval food) into the environment.

Can fleas bite through clothes?
Fleas can’t bite through most clothing. Exceptions are tight-fitting, thin fabrics.

How can I prevent flea bites?
Wear pants and socks, tucking the pant legs into the socks. Permethrin insect repellent for clothes can also deter the fleas.

How do I treat flea bites?
Flea bites will heal on their own. However, the irritation can be reduced by using hydrocortisone cream or other anti-itch lotions.

Please leave a comment below if you have any questions that weren’t addressed, and I’ll add them to the list.

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  • Denise Simpson December 26, 2015, 4:12 am

    This is absolutely the best web site I have found for helping me to competently identify fleas on my cats. I live in a very small space with two cats that came to me at different times as stays. I took them in both are males so needed neutering and of coarse vaccinations. I find myself obsessively checking them for fleas so I’m so happy to have found your web site
    Thank you.
    This is the first time I have made a comment found your site just ten minutes ago.

    • Adam Retzer December 26, 2015, 6:32 pm

      Thanks for the kind words. It means a lot to know people are benefiting from the content!