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INTRODUCTION.
Their common name comes from one of their favorite hosts, dogs, the other being rabbits.
Like other fleas found in homes, they cause discomfort by biting, but they can also
transmit several diseases such as plague and murine typhus. Dog fleas are found throughout
the United States and the rest of the world.
RECOGNITION.
Adults about 1/8" (2.5 mm). Body laterally flattened (side to side); wingless. Color
brownish black to black, but reddish black when full of blood. Female's head less than
twice as long as high. Compound eyes well developed. Both genal and pronotal combs
present, each composed of 16 spines, and genal comb's spine I (anterior most) shorter than
spine 11 (adjacent spine to posterior/rear). Femur of hind leg with 10-13 bristles on
inner side. Abdominal terga (dorsal plates) 2-6 with a single row of bristles. In
addition, antennae short, 3-segmented; oceiii lacking; legs long, coxae large, tarsi
5-segmented; usually jumping insects; mouthparts piercing-sucking with well- developed
palps. Mature larvae about 1/8-1/4" (3-5.2 mm) long. Larvae whitish, slender,
eyeless, and legless. With a well-developed head. Anal struts/hooks 2, small. With
moderately long, backward-projecting hairs (setae) encircling each segment. Last abdominal
segment (10th) with 3 ventrolateral hairs (setae). Description is same as for cat and
oriental rat fleas.
SIMILAR GROUPS.
European mouse flea (Leptopsylla segnis) has genal comb with only 4
spines.
Rabbit flea (Cediopsylla simplex) with genal spines oriented
vertically (vs. horizontal),, comb spines with blunt/rounded ends.
Cat flea (Ctenocephalides felis) with head twice as long as high,
genal comb with Ist 2 anterior spines of about equal length, and hind femur with 7-10
bristles on inner side.
Other fleas (various families) lack having both pronotal and genal
combs or if both present, then either have abdominal combs or have fewer than 16 spines in
pronotal comb (cat flea with 16 pronotal spines, see above).
BIOLOGY.
Females lay 4-8 eggs after each blood meal, laying some 400-500 during their lifetime. The
eggs are not glued/stuck to the hairs or body but are deposited on or between hairs, or in
the nest or bedding material. Hence, eggs deposited on the animal either fall or are
shaken off, and are frequently found in cracks and crevices where pets sleep or frequent.
Eggs are oval, whitish, and about 1/64" (0.5 mm) long. They usually hatch in 1-12
days. Flea larvae move about using the setal rings and abdominal struts/hooks. They have
chewing mouthparts and feed on organic debris but almost all require dried fecal blood in
order to complete development; they do not bite but feed on adult flea fecal blood. Larvae
require high relative humidity (45-95%) and 1-2 weeks to several months to go through 3
instars. Last instar larvae spin a cocoon and incorporate surrounding debris on its
surface which provides camouflage. Under favorable conditions, the pupal stage may last
4-14 days or maybe up to a year under harsh conditions. The pre-emerged adult remains in
the cocoon for up to 20 weeks, where it is protected from adverse conditions, including
pesticides; it can survive here for several months on stored body fat. Adults are
stimulated to emerge from the cocoon by mechanical depression of the cocoon, an increase
in temperature and/or carbon dioxide, and possibly vibrations. Larvae and pupae are
typically found where an animal sleeps or frequents. Adults usually begin to seek a blood
meal on the second day after emergence. Once on a host, they tend to spend all of their
time on the host, feeding, mating, and laying eggs, unless dislodged. Although they have a
preferred host, they will readily bite and can survive using other species as hosts.
Depending on conditions, adults usually live only several days because normal dog grooming
removes up to 50% or more of the fleas; otherwise, they can survive for several months.
Dog fleas are known to be vectors of the disease organisms causing both plague and murine
typhus. Dog fleas can also serve as an intermediate host for the dog tapeworm, Dipylidium
caninum (Linnaeus), and the rodent tapeworm, Hymenotepis diminuta (Rudolphi). These
tapeworms occasionally infest humans, particularly very young children.
HABITS.
It is not necessary to have pets in the building in order to have fleas present. Since
fleas can jump about 6" (15 cm) vertically, they can easily hitch a ride on shoes,
trousers, etc. Many vacationers who may have been unaware of the few adult fleas present
in their home, are often greeted and severely attacked by fleas upon their return. Fleas
can be present even if the building has been vacant of animals and people for as long as 6
months or so. This situation can occur because of the potentially long pupal period,
adults can live for months without food, and because fleas have not been removed via
normal vacuuming. Also, fleas are normally removed from the interior environment by taking
up residence on the pet(s).
Fleas are typically found where animals sleep or frequent, including along their usual
avenue of travel, because this is where eggs and adult fecal blood accumulate. Most larvae
will be found in similar places but especially in areas with high moisture which is
necessary for their survival. Pupas will be found in the same situations as larvae. Such
places include both indoor and outdoor situations. Dog fleas are also found on other urban
hosts such as rabbit, spotted skunk, opossum, occasionally rats, and rarely cats. Flea
larvae die at relative humidities below 45% and above 95%, and hence, are rarely found
outdoors in and climates. Larvae fail to develop at temperatures below 55'F (1 3'C) and at
or above 95'F (35'C).
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