PARASITES AND PARASITIC DISEASES OF DOMETIC ANIMALS
The life cycles of all fleas are basically the same. They consist of six stages -
egg, 3 larval stages, pupa and adult (male or female). The general cycle is
illustrated here using the specific life cycle of Ctenocephalides, which contains
the two species (C. canis and C. felis) of importance in dogs and cats.
Adults are the only flea stages spending most of their time on a host. They leave
the host occasionally and usually only when one host makes contact with another. All
other flea stages - eggs, larvae and pupae - are found in the immediate environment of the
host. In dogs and cats this would primarily include places in the home and kennel used for
resting and sleeping. Therefore by far the greatest majority of fleas are found
concentrated in the host's environment as eggs, larvae, pupae and newly emergent adults
and only a small proportion of the total flea population is found on a host as feeding,
reproducing adults plus newly laid eggs and hatched larvae that have not dropped
Adult Ctenocephalides lay eggs on their hosts. These are approximateley 0.5mm long and
white in color. At optimal conditions of temperature and humidity, first stage larvae will
hatch about four days later. A mixture of eggs, L1s and adult flea feces drop off the host
into the environment where most of the cycle develops. Larvae feed on feces from adult
stages and this largely consists of dried host blood and tissue ingested by these feeding
adults. Larval stages molt twice and will reach the third stage (L3) in two weeks when
their environment is warm and moist. L3s which are about 5mm long now spin a cocoon and
inside each pupal case transform (metamorphose) into an adult.
Adults emerge from the pupa and seek a host to feed and reproduce. Females will lay
eggs within 48 hours of feeding on their new host
Under optimal conditions of a warm, moist environment the whole flea life cycle may be
completed in three weeks.
Temperature and moisture are the primary factors controlling the flea life cycle.
Studies have shown that the Ctenocephalides life cycle stages will develop
within a range of temperatures from 13'C to 32'C and a range of relative humidity from 50%
to 92%. The life cycle will be completed in 2 to 3 weeks at the high ends of these ranges
and may take as long as 3-4 months at the low ends.
Temperatures greater than 35'C will kill developing larvae and pupae.
Adult fleas may survive from 2 to 6 months in the absence of a host for feeding.
However, when hosts are present, adult fleas will spend the majority of their time
feeding and reproducing on their hosts.
Adults fleas are fairly long-lived. Most will live up to one year and some can live as
long as two years under natural conditions if they are unthreatened by chemical control