Fleas
P.G. Koehler and F. M. Oi
External parasites are 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.
CREDITS: James Castner, University of Florida
Figure 1. Cat flea adult.
Biology
The female flea lays her tiny, white eggs ( Figure 2 ) loosely on the
hairs, in the feathers, or in the habitat of the host. The eggs readily fall
off the host onto the ground, floors, bedding, or furniture. Some fleas can
lay 500 eggs over a period of several months by laying batches of three to
eighteen eggs at a time. The tiny eggs hatch in one to twelve days after being
deposited. The white, worm-like larva ( Figure 3 ) avoids light and feeds on
particles of dead animal or vegetable matter generally present in cracks and
crevices. Within 7 to 14 days, unless food has been scarce, the third larval
stage is completed, and the larva spins a tiny cocoon ( Figure 4 ) and
pupates. Usually after a week the adult flea emerges and begins its search for
blood.
CREDITS: James Castner, University of Florida
Figure 2. Flea eggs and feces.
CREDITS: James Castner, University of Florida
Figure 3. Flea larvae.
CREDITS: James Castner, University of Florida
Figure 4. Flea cocoons.
Fleas are known to remain in the pupal stage from five days to five weeks
in the absence of hosts. Adults emerge from the pupal case when vibrations
from pets or humans let them know a host is near. This is one reason why
people returning to an unoccupied home may suddenly be attacked by an army of
fleas.
Adult fleas must feed on blood in order to reproduce; however, adults can
live for long periods without feeding. Fleas usually live and breed most
heavily where pets rest. Persons coming near these resting places are also
subject to attack. If fleas are established in a home, they will feed on man
as well as on the pets. The usual places of attack are the ankles and lower
portions of the legs.
The so-called "sand-flea" is nothing more than a common flea that is
breeding outdoors in the soil. Contrary to belief, fleas cannot go through
several generations without having a blood meal.
The entire life cycle ( Figure 5 ) of a flea can require from two weeks to
two years. Hot, wet, summer months favor egg laying. Hot, dry periods give
maximum adult production, so greatest adult flea populations are produced in
August to September.
Figure 5. Flea life cycle.
Importance
Fleas often breed in large numbers where pets and other animals live. Pets
infested with fleas bite and scratch themselves constantly. Their coats become
roughened and the skin can become infected. Symptoms of sensitized hosts are
often mistaken for mange. Cat fleas and dog fleas may be intermediate hosts
for the dog tapeworm.
Some people suffer more than others from flea bites. The bites can cause
intense itching often resulting in secondary infection. The usual flea bite
has a small red spot where the flea has inserted its mouthparts. Around the
spot there is a red halo with very little swelling. Many people do not react
to flea bites at all while others are sensitive and suffer severe allergic
reactions. Fleas may also vector such human diseases as plague, typhus, and
tularemia.
Control
Flea control is difficult for pet owners to implement because two things
must be done: (1) treat the pet and (2) treat the premises. Pet treatment
alone is not sufficient because the animal quickly becomes reinfested from
untreated premises.
Humans are often bitten by fleas when they enter infested areas.
Pet Treatment
Flea collars are sold under several trade names and are sometimes
effective on small, short-haired dogs or cats that are not subjected to
flea-infested areas.
Other treatments are usually necessary to supplement flea collars on
large, long-haired pets that are allowed freedom outdoors. Also, some pets may
be allergic to flea collars. Ultrasonic flea collars have not been found to
kill or repel fleas.
Veterinarians may prescribe or apply pesticides not available over the
counter. Oral flea medication prescribed by veterinarians has provided control
of fleas when pets are not allowed outdoors and effective flea control is
accomplished in the house and yard. Topical or spot treatment has provided
effective residual control.
Pets may be combed or shampooed frequently to remove adult fleas before
they can irritate the pet or lay eggs. Frequent removal of fleas can quite
effectively reduce flea infestations.
To be certain pets remain free of fleas, it is necessary to make routine
use of flea control products, especially if pets are allowed to contact
infested animals or premises.
Dust treatments should be applied carefully and rubbed into the fur
working from the head to the tail. Special attention should be given to the
top of the head, the neck, and the back. Apply treatments outdoors so fleas
that leave the animals do not remain indoors.
Premise Treatment
Pets become reinfested with fleas from premises. For the most effective
control, sleeping areas, bedding kennels, and other areas frequented by the
animal should be treated at the time the pet treatment is made. Treatments may
or may not include the use of pesticides.
Nonpesticidal premise control includes thorough and frequent cleaning of
the house. All rugs should be thoroughly cleaned with a vacuum cleaner or a
steam cleaner. Infested furniture, pet baskets, and cracks should be
thoroughly cleaned to prevent the larvae from finding food. Dirt which is
collected should be disposed of immediately to destroy fleas and flea larvae.
Many people remove pets from the home to attempt flea control. Flea
infestations usually become more evident when pets are removed. Although, the
hungry adult fleas prefer to feed on cats and dogs, when the pet is removed,
the fleas overrun the home, frequently attacking humans. Dogs and cats can be
used to attract fleas from the premises. Recommended pet treatments at
frequent intervals can be used to kill the fleas.
Insect growth regulators (IGRs) are the most effective chemicals and are
found in some indoor, space, and surface treatments. These may be used in conjunction with residual sprays to quickly reduce adult populations. IGRs prevent flea larvae from turning into adults, and have a residual effect of almost three
months. For IGR applications to be effective, pets must not be allowed access
to heavily infested areas outdoors; otherwise adult fleas will constantly be
carried indoors by the pet.
Insecticides should be applied inside the house carefully as light, spot
treatments to areas where fleas are known to be hiding. These can be applied
indoors as crack and crevice or surface treaments. For heavy
infestations indoors, or when egg masses of ticks hatch, space sprays can be
applied to give quick knockdown . Outdoors, infested areas should be
treated by applying a broadcast treatment of insecticide to the landscape
Copyright Information
This document is copyrighted by the University of Florida, Institute of
Food and Agricultural Sciences (UF/IFAS) for the people of the State of
Florida. UF/IFAS retains all rights under all conventions, but permits free
reproduction by all agents and offices of the Cooperative Extension Service
and the people of the State of Florida. Permission is granted to others to use
these materials in part or in full for educational purposes, provided that
full credit is given to the UF/IFAS, citing the publication, its source, and
date of publication.
11/29/04
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