Cat Flea

To successfully control flea infestations on pets, one must understand one’s adversary. There are primarily four species which infest cats and dogs,* Ctenocephalides felis felis (cat flea), Ctenocephalides canis (dog flea), Pulex simulans, and Echidnophaga gallinacea (poultry sticktight flea). When viewing literature on the cat flea remember that the literature is not referring to fleas that are found on cats but to a genus of fleas. Ctenocephalides felis felis is the subspecies with which one normally deals in North America.**

Not only can cat fleas produce anemia as a result of iron deficiency, they produce allergic dermatitis in dogs and feline miliary dermatitis in cats. They do this by injecting antigenic material from the salivary glands of the flea into the blood stream of the host.  Bacterial infections associated with cat flea infestation are Rickettsia felis (Typhus), Bartonella spp, Bartonella henselae, (cat scratch fever)  and Mycoplasma haemofelis (feline infectious anemia). Fleas also serve as the intermediate host for flarid and cestode parasites. Cat fleas are ectoparasites which means they permanently live on the host. Though fleas can transfer from host to host, new infestations usually occur from newly matured fleas emerging from the environment.

Flea Anatomy

     Cat fleas are laterally compressed, wingless, 3 mm long and reddish-brown to black in color.  Female cat fleas are larger than the males. Males have snail shaped genitalia.   Cat fleas have a sloping forehead and  ctenidia.*** They do not have compound eyes.

The head of the Cat Flea

Their hind legs are longer than their front legs to facilitate jumping.  The muscles of their legs are made from a protein called resilin. This protein produces extreme energy.  Cat fleas can jump 8 inches horizontally and 13 inches vertically. To put this into prospective, if a cat flea were as big as a dog, it could jump one quarter mile.  The cat flea’s body is designed to slip easily through animal hair.  The setae are arranged in dorsal-ventro rows, which point posteriorly.  The spacing between the rows correlates to the host’s hair shaft.  This design keeps the flea from being dislodged during host grooming. When  fleas feed their lower jay, which is jagged moves back and forth, cutting the host’s skin.  The epipharynx (elongated tube) is inserted into a blood vessel. Saliva then enters the wound. Cat fleas are not cold-tolerant but will survive in areas which are protected from the cold.  When feeding the female excretes incompletely digested blood, which dries into pellets (flea dirt).  The larvae feed upon these pellets.

The Flea Life Cycle

     Cat fleas are holometabolous insects. This means they go through metamorphosis, moving from egg, larva, pupa, to adult.  After feeding, around 8 to 24 hours, cat fleas mate on the host.  Egg production occurs 24 to 36 hours after the female’s first meal.  The un-sticky eggs are laid within the hairs of the host.  The eggs then drop off into the environment.  Female cat fleas can produce up to 1300 eggs within 50 days of the first feeding. They can continue to produce eggs for more than a 100 days.

Flea Egg

Flea eggs need an environment which is warm, ranging from 75 to 85 degrees Fahrenheit.  Humidity must be from 50 to 90 percent. If the right conditions exist eggs hatch from one to 10 days later.  Cat flea larvae avoid light. They crawl into dark places, usually at the base of carpets, in cracks or outside at dirt level where they feed on flea dirt and organic matter. They need moisture and warmth to grow and thrive. Cat flea larvae go through three molts before beginning the pupal casing.

Cat Flea Larvae

The flea larvae case is made from a combination of debris and silk produced from larvae saliva. Within the home the debris consist of hair, dust, lint, and carpet and furniture materials. The cocoon is water-tight and virtually invisible. A flea may remain in the pupal stage for up to a year.  It will not emerge if a host is not available because without a meal soon after emerging it will die. If conditions are correct, the flea will emerge in about a week.

Cat Flea Pupal

Vibrations, exhaled carbon dioxide, and body heat from the host stimulate fleas to emerge from the cocoon. The newly emerged flea begins to feed immediately upon coming in contact with the host.  It secretes salvia into the wound which softens the skin and prevents clotting. The life cycle begins all over again.



Adult Fleas


Why Understanding the Life Cycle of the Flea is Important


To understand how cat flea infestations can become so large and are so hard to eliminate, it is critical to understand the life cycle of the flea. Understanding where and how the flea reproduces and where the larva and pupa hide permits one to control the flea populations through its entire life cycle. Simply killing fleas on the host will not end a flea infestation.  It is important to address the environment as well. From egg to larval to pupa to adult, all areas of the life cycle must be addressed to successfully treat a flea infestation and stop the next generation of fleas from emerging.

Our next blog will address the effectiveness and dangers of chemical treatments.

*This series of articles deals primarily with fleas which infest cats and dogs. Other species will be mentioned when appropriate.

**Ctenocephalides felis damarensis and C felis strongylus occur in East Africa and C felis orientis occurs in India and Australia.

*** A series of thick, sharp spines which look like five teeth on a comb. Cat fleas have these on their head (genal ctenidium) and on the posterior portion of first thoracic tergite (pronotal ctenidium).

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