1-7.
FLEAS
a. Fleas (order Siphonaptera) are small insects flattened from side to side,
usually dark in color, generally possessing many stiff bristles (see figure 1-14). Their
legs are well developed and the hind legs are especially strong. Fleas are excellent
jumpers and some species are able to jump 50 times their length. Flea eggs drop off
the host and fall amongst debris on the ground. The active, immature stage is a maggot
Iike, legless larvae (see figure 1-15). The larvae do not Iive on the animal but in the
nest of the host in the yard or wherever the host is found. In buiIdings with pets, flea
larvae thrive particularly well in carpets where they feed on organic debris such as dried
blood, cast skins, or excreta. Larvae undergo three molts during development, and the
entire larval period is frequently as short as 2 to 3 weeks. The larva spin siIken cocoons
just prior to pupation and camouflages them with bits of debris. Here the pupae develop
into adults during a resting period that varies in length from a few days to a year or
more. Adults are normally long Iived and feed on a wide variety of animals including
humans.
Figure 1-14. Adult Flea
Figure 1-15. Flea larva.
b. Fleas are active biters and proven vectors of human disease. The oriental rat
flea, Xenopsylla cheopis, is the most important vector of bubonic plague and murine
typhus. Other species of fleas associated with rodent hosts may also be vectors of
plague in human, but are not considered as important as Xenopsylla cheopis. There
are approximately 1,500 species of fleas. Besides being vectors of disease, fleas can
be very annoying and their bite may produce extreme itching and dermatitis in sensitive
individuals.
MD0170
1-13