Overview
Fleas are external parasites generally found on or in the skin and are important pests because they bite or annoy both humans and their pets. Fleas, mange mites, and ticks are the most frequently encountered and most troublesome pests that attack humans and their pets.
Fleas are small (1/16"), dark, reddish-brown, wingless, blood-sucking insects. Their bodies are laterally compressed, (i.e., flattened side to side) permitting easy movement through the hairs on the host's body. Their legs are long and well adapted for jumping. The flea body is hard, polished, and covered with many hairs and short spines directed backward. The mouthparts of an adult flea are adapted for sucking blood from a host.
Fleas may attack a wide variety of warm-blooded animals including dogs, humans, chickens, rabbits, squirrels, rats and mice.
Figure 1. Cat flea adult.CREDITS: James Castner, University of Florida
Flea Allergy Dermatitis (FAD)
Flea Allergy Dermatitis (FAD) also termed flea-bite hypersensitivity, is an allergic skin reaction to flea saliva. It can occur in both dogs and cats when fleas bite them. Dogs and cats rarely get this form of allergy before six months of age. Usually, the age of onset is around three-to-six years of age.
Frequently Asked Flea Control Questions
Q: My daughter gets bitten by fleas while I am never bothered. Why is this?
A: Blood feeding insects are attracted to chemicals emitted from the body (sweat, exhalation, etc.). Some people just smell more attractive than others to certain insects. Individual sensitivity to the bite is another reason. To some, flea bites are extremely irritating while other people hardly notice them. This is caused by an allergic response to the flea saliva and occurs in varying degrees among people.
Q: I have bombed my house for fleas three times this month and still have them. Why?
A: It is likely that you are seeing adults emerge from cocoons that were produced before you bombed. The cocoons are deep within the carpet and treatment may not have reached them. If you did not treat your yard new fleas may be coming indoors on you or your pets. If the foggers you used contained pyrethrins or pyrethroids, you probably only killed larvae and adults. Insect growth regulators are available in foggers and will prevent development of immature fleas.
Q: I just moved into a new apartment. It is infested with fleas. Where did they come from and what can I do?
A: The people living there before you probably had a pet. Even if the apartment was treated with insecticides before you moved in, the treatment may not have penetrated the carpet to kill developing pupae. Treatment is described above.
Q: When we go on vacation, we board our dogs at the kennel and leave the house closed up for three weeks. As soon as we get home we are attacked by fleas. The dogs have been away. What is going on?
A: The fleas that were in the egg and larval stage have pupated and matured and were waiting in their cocoons for the proper stimulation to emerge (vibration, carbon dioxide). In order to keep this from happening, next time treat your home with an insecticide that kills adult fleas and an insect growth regulator to prevent immature fleas from developing.
Q: What is the difference between dog fleas and cat fleas?
A: Cat fleas are the main flea on both cats and dogs in North America. Dog fleas are found in Europe. They are distinguished by a slight morphological difference which is only detectable under high magnification.
Q: What are sand fleas?
A: "Sand fleas" or "beach fleas" are common names for small orange amphipods found along the beach. They are distant relatives of true fleas, and are not even insects (they have more than six legs). Also, some people may refer to fleas that just happen to be developing in sandy areas as "sand fleas".
Footnotes
1. This document is ENY-205, one of a series of the Entomology and Neamatology Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Date first printed July 1993. Revised: February 2003.
2. P.G. Koehler, professor/extension entomologist and F. M. Oi, assistant extension entomologist, Entomology and Nematology Department, Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611.