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Fleas |
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Description
and Behavior
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Life Cycle
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The life cycle of a flea consists of four stages: the egg, the larva, the pupa, and the adult. Eggs are deposited either on the pet, in the pet’s bedding, or in cracks and crevices of floors. Eggs placed on the pet are not firmly attached and soon fall off. In about a week, the eggs hatch into immature fleas called larvae. Flea larvae are very different from adult fleas. They are wormlike, lack legs, and do not feed on fresh blood, but live on organic matter, including dried particles of blood and excrement voided by the adult fleas. In about 12 days, the larvae are fully grown and change to the pupal stage which then changes into the adult flea. Adults feed more than once a day on fresh animal blood. They may live as long as a year and in some cases, even longer. Fleas may be present, though unnoticed, all year in the house but frequently become troublesome following return from a vacation. Fleas inside an empty house soon become extremely hungry. When the vacationers return, they are greeted by these neglected fleas who now make their presence known by biting avidly. Flea bites on humans are generally most prevalent on the ankles and lower portion of the legs. |
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Public Health Importance |
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Fleas can transmit a number of diseases to man, most important of which is plague. In the 14th Century, this disease, known as the “Black Death”, killed a quarter of the population of Europe (some 25 million people). In 1665, an epidemic in London killed 70,000 persons out of a total population of 460,000. In 1900, the plague came to North America. From 1900 to 1925, 432 cases were reported in the United States. There have been no epidemics of plague reported in the United States since 1925, but plague is present in the wild rodent populations of the western states, and generally a few cases in plague, in humans, occur each year from this source. In 1980, nine cases of plague were reported (five from New Mexico, two from California and two from Nevada). Murine typhus, a disease primarily affecting rats and mice, can be transmitted to man by infected fleas. When a flea feeds, it usually defecates at the same time, and it is believed that the transmission of the murine typhus pathogen occurs by scratching the infected feces into the would. About 40 cases of murine typhus are reported each year in the United States. |
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Management
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of pets can be accomplished in a number of ways. The most common treatment
involves the use of shampoos which contain a insecticide. This
treatment is effective for only adult fleas that are on the pet when the
shampoo is applied and is usually a good way to “clean” a pet
prior to transporting them from one location to another (i.e.. from a
boarding kennel to your home). Traditionally, dusts containing
an insecticide have provided longer residual effect against fleas on pets.
The dusts are sprinkled onto the animal, thoroughly rubbed into the coat
and any excess is brushed out. Flea sprays are effective in reducing
or repelling fleas from pets. They also have a longer residual effect
then shampoos but like dusts must be applied on a regular basis as described
on the container label. Recently, several types of insecticides which
are given orally as a systemic treatment to pets in tablet or capsule
form has shown promise in controlling flea infestations. These products
are prescribed by veterinarians and either kill the adults which take
a blood meal from the treated animal, or render the fleas unable to reproduce
viable offspring hence eliminating future generations. Another treatment,
which can be prescribed by veterinarians, is referred to as a spot-on
and involves the application of a small amount of liquid insecticide to
the pet between the shoulder blades. This application remains effective
for up to a month and will kill adult, biting fleas. These last two options
(systemic and spot-on) are perhaps the best choice for most pets and pet
owners.
A number of insecticides are labeled for control of fleas in residences. These materials are sprayed onto carpets and into cracks and crevices throughout the building. The benefit of using these materials is that they provide an immediate reduction in the numbers of adult, biting fleas. Unfortunately, most of the effective materials can only be purchased by certified professionals. Homeowners can have an impact on the numbers of fleas within their homes without the use of pesticides, by thoroughly vacuuming all carpets, floors and upholstered furniture on a daily basis for several weeks. The vacuum cleaner bag should be disposed of after each vacuuming to prevent the adult fleas from crawling out of the cleaner. This is a good method for individuals with known insecticidal sensitivities and allergies and, if used in combination with the systemic and spot-on treatments for pets, will significantly reduce or eliminate flea populations. |
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Warning
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Pesticides are poisonous. Read and follow directions and safety precautions on labels. Handle carefully and store in original labeled containers out of the reach of children, pets, and livestock. Dispose of empty containers right away, in a safe manner and place. Do not contaminate forage, streams, or ponds. Authored by: Steve Jacobs, Sr. Extension Associate December
1998 ©
The Pennsylvania State University 2003
This publication is available in alternative media on request. Penn State is committed to affirmative action, equal opportunity, and the diversity of its workforce. Return to Entomological Notes Listing Home | Research | Extension
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