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| flea anatomy |
Fleas. They make pets' lives miserable, and humans begin to itch just
at the thought of them. Vets are often asked what pill, drug, dip,
collar, or shampoo works the best to get rid of these persistent
parasites. The answer is there is no single method or insecticide that
will completely eradicate (or at least control) a flea problem.
Part I of this article is to give some insight to the biology of
the flea. Why go back to biology? Because the flea life cycle is fairly
complex, and understanding the various stages will make it easier to get
rid of fleas. Part II of this article will discuss why multiple approaches are needed to control/eradicate fleas.
The life and life cycle of the flea
There are many hundreds of species of fleas. Collectively, all of the species of fleas are categorized under the order name of
Siphonaptera. The cat flea,
Ctenocephalides felix, is the most commonly found flea in the US and infests cats, dogs, humans, and other mammalian and avian hosts.
Fleas
thrive in warm, moist environments and climates. The main flea food is
blood from the host animal. Host animals are many species - cats, dogs,
humans, etc. Fleas primarily utilize mammalian hosts (about 95%). Fleas
can also infest avian species (about 5%). Flea saliva, like other biting
skin parasites, contains an ingredient that softens, or "digests" the
host's skin for easier penetration and feeding. The saliva of fleas is
irritating and allergenic -- the cause of all the itching, scratching,
and other signs seen with
Flea Allergy Dermatitis, or FAD.
Fleas
have four main stages in their life cycle: egg, larva, pupa, and adult.
The total flea life cycle can range from a couple weeks to several
months, depending on environmental conditions.
ADULT: The
adult
flea is very flat side to side. There are hair-like bristles on the
flea body and legs to aid in their navigation through pet hair. Fleas
have 3 pairs of legs, the hindmost pair designed for jumping. Fleas are
well known for their
jumping abilities. Click here to learn more about
flea anatomy.
Adult fleas prefer to live on the animal and their diet consists
of blood meals courtesy of the host animal. The female flea lays white,
roundish
eggs. The adult female flea can lay up to 50 eggs per day
1, 500-600 eggs
2 over several months.
EGG: The
eggs
are not sticky (like some parasites), and they usually fall off of the
animal into the carpet, bedding, floorboards, and soil. When the flea
egg hatches varies -- anywhere from two days to a few weeks,
depending on environmental conditions. The
larva emerges from the
egg using a chitin tooth, a hard spine on the top of the head that disappears as the flea matures.
LARVA
(plural = larvae): The larval stage actually has three developmental
stages within this stage. Larvae are about 1/4" (6.35 mm) long, and
semi-transparent white. They have small hairs along their body and
actively move. They eat the feces of adult fleas (which is mostly dried
blood) and other organic debris found in the carpet, bedding, and soil.
Depending on the amount of food present and the environmental
conditions, the larval stage lasts about 5 to 18 days (longer in some
cases) then the larva spins a silken cocoon and
pupates.
PUPA
(plural = pupae): The pupa is the last stage before adult. The adult
flea can emerge from the cocoon as early as 3 to 5 days, or it can stay
in the cocoon for a year or more, waiting for the right time to emerge.
When is the right time? (Never, say pet lovers everywhere!) Stimuli such
as warm ambient temperatures, high humidity, even the vibrations and
carbon dioxide emitted from a passing animal will cause the flea to
emerge from the cocoon faster. This brings us back to the
adult flea.
The entire life cycle is quite variable, as evidenced by the
variability in each life stage progression. As mentioned above, the
cycle can be as short as two weeks or as long as two years. That is why
it is so important to remain vigilant, even when a flea problem is
thought to be under control! The
duration of flea season varies with location.
In
Part II of this article, various methods of flea eradication will be discussed, both for the pet(s) and for the environment.