Fleas: They are happiest at home

May 01, 2008

The adult cat flea (Ctenocephalides felis) is a ubiquitous, enterprising and persevering insect. The cat flea is the most dominant, competitive and most common flea associated with domesticated animals today.

It has been linked to numerous human diseases (such as the plague or typhus) and remains the scourge of veterinary medicine.

Cat fleas are known to infest numerous hosts, including the domesticated cat, dog, ferret and many other wild animals. They have been identified in large numbers on raccoons, opossum, skunks, domesticated rabbits, coyotes, foxes, mongooses (in parts of Hawaii) and even koalas. They are known to infest cows, goats and certain types of poultry.

Busting rumors

Unfortunately, most owners, pet-store personnel and groomers tend to perpetuate numerous false facts about the hosts of the adult cat flea. It is rarely, if at all, found on squirrels and wild rabbits. The belief that squirrels are promoting and infecting the environment is a common misconception, especially among pet owners. The real culprits are nocturnal animals such as opossum, raccoons, feral cats and skunks frequenting pet owners' backyards and gardens. This environmental contamination can lead to adult flea infestations on pet animals, and subsequent problems in homes.

This leads to another of the common misconceptions about fleas: They jump from one infested pet to another. What is fascinating and amazing is that many veterinarians believe this myth.

The adult cat flea is very much happy and content to live on a cat or dog. The adult flea has everything it needs. They have a warm place to live, a place to hide from predators and a constant source of nutritious food (blood meal of the host).

Typically, fleas do not leap from host to host as a rule. This phenomenon has been observed when there is a severe overpopulation of adult fleas on a pet.

Hitching a ride

The problem begins when these adult fleas begin to breed (especially in flea-allergic pets). Adult fleas feed on the host within a few minutes or less after establishing a safe home. Breeding begins (usually within a day or two after feeding) followed by egg production. On any given host there are about twice as many adult female fleas as males. These female fleas are capable of laying up to 40 to 50 eggs per day.

Most eggs desiccate in the outdoor environment after dropping off the host. Most experts believe that 50 percent to 70 percent or more of the ova produced by a female flea may be viable. It appears that the outdoor environment is much harsher than indoor environments. Lack of humidity (50 percent or less) is second to lack of a food source as the most lethal environmental condition immature fleas are exposed to. Egg production and hatching eggs begin within 48 hours. Eggs are not sticky, and fall to the ground. As mentioned previously, ova do not survive without adequate moisture (humidity). Surviving eggs will begin to hatch into larvae. Larval survival is dependent upon adequate moisture as well. Thus, desiccation of larvae can occur. Larvae will survive in soil, grass, carpets, unwashable pet bedding, as well as within cracks between hardwood floors. Larvae may drown in soil that is over saturated. The main food source for these larval organisms is the adult-flea feces that deposits in the environment where the animal may frequent. Egg survivability and larval development is dependent upon temperature. The ideal temperature is 65F-75F degrees (with relative humidity around 75 percent). Keep in mind that humidity is much higher deep in the carpet pile or soil, compared to the humidity measured in the air.

It is important to point out the amazing survivability of fleas and the immature stages. All stages of the flea life cycle can survive temperatures as low as 28F (for brief periods of time) and as high as 95F. Most immature stages do not survive above 95F, especially in full sun.

In colder climates, like the Northeast, fleas may continue to survive living on hosts in pets or wild-animal bedding, in carpets, in freeze-protected areas around homes or in wild-animal burrows.