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INTRODUCTION.
Fleas are one of the more important groups of insect pests because they not only cause
discomfort by biting, but they can transmit several diseases such as plague and murine
typhus. Cat fleas are found throughout the United States and the rest of the world.
RECOGNITION.
Adults about 118" (2.5 mm) long. Wings lacking. Body laterally flattened (side to
side). Color brownish black to black, but reddish black when full of blood. Female's head
twice as long as high. Compound eyes well developed. Both genal and pronotal combs
present, each composed of 16 spines, and genal comb's first 2 anterior spines of about
equal length. Femur of hind leg with 7-10 bristles on inner side. Abdominal terga (dorsal
plate of segments) 2-6 with a single row of bristles. In addition, antennae short,
3-segmented; ocalli lacking; legs long, coxae large, tarsi 5- segmented; usually jumping
insects; mouthparts piercing-sucking with well-developed palps. Mature larvae about twice
the adult length. Larvae whitish, slender, eyeless, and legless. With a well-developed
head. Anal hooks 2, small. With moderately long, backward-projecting setae (hairs)
encircling each segment.
SIMILAR GROUPS.
European mouse flea (Leptopsylia 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.
Dog flea (Ctenocephalides canis) with head length less than twice
height, genal comb with spine I (anterior most) distinctly shorter than spine 11 (adjacent
spine to posterior/ rear), hind leg femur with 10- 13 bristles on inner side.
Other fleas (various families) lack having both pronotal and genal
combs or if both pronotal and genal combs present, then either have abdominal combs or
have fewer than 16 spines in pronotal comb (dog 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 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 then 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 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. Adults
are stimulated to emerge from the cocoon by mechanical depression of the cocoon, an
increase in temperature, and possibly vibrations. Larvae and pupae are typically found
where the animal sleeps or frequents. Adults usually begin to seek a blood meal on the
second day after emergence, but can live for several months on stored body fat. 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 cat grooming removes up to 50% of the fleas; otherwise, they
can survive about a year.
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,
are often greeted and severely attacked by fleas upon their return. This can occur 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. Pupae will be found in the same situations as larvae. Such
places include both indoor and outdoor situations. Cat fleas are also found on other urban
hosts such as opossum, fox, mongoose, and occasionally rats. 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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