three molts, they grow to near l/4 inch but are still
difficult to see. The entire larval stage may take only
one week under favorable conditions, or it may be
prolonged into several months.
The legless larvae can disappear with remarkable
speed (into carpets, pet bedding, etc.) moving by use
of a pair of spines at their rear and long (hut nearly
invisible) hairs on each segment. Larval fleas are
scavengers and do not suck the hosts' blood or live on
hosts. Cat flea larvae have chewing mouthparts which
they use to eat specks of dried blood (see adults).
Fleas inject an irritating saliva when they feed.
[when they are full, the blood turns them to a near-
The bite irritation causes the host to scratch and shake,
Like many insects that live in large populations
dislodging the eggs. The females digest the host's
blood and excrete a corkscrew shaped string of black,
(e.g., pantry pests), mature flea larvae crawl away
nearly dry blood. This fecal blood breaks up in
from the area where they developed, and work their
pepper-like specks that are also scratched off into the
way into cracks or under the edge of the pet bed, rugs,
pet sleeping or resting areas.
or carpeting. These mature larvae spin a loose, white,
silken cocoon in which to pupate. The cocoon often
Flea Bite and Flea Allergy
gets covered with dirt particles and other detritus
during its construction.
The flea bite is accompanied by secretions of
saliva that prevent the host's blood from coagulating [a
aspect accompanying the bites of many blood-sucking
insects]. The saliva contains several chemicals that
Shortly after making the cocoon the larva molts
cause irritant reactions, sometimes including
and forms a white pupa. The pupa becomes adult but
hypersensitivity to subsequent flea bites. This
does not emerge immediately, rather, it remains
sensitivity often results in flea allergy dermatitis,
immobile in a form called the "pre-adult" until
expressed by hair loss, excessive scratching, skin
stimulated to leave the cocoon. This pupal stage is
completed within one week to ten days, but the pre-
adult form may remain in the cocoon for months.
Various stimuli guarantee the flea will leave the
cocoon only at a favorable time: being stepped on by
the pet, carbon dioxide being exhaled by a host, or,
encountering a sufficient number of warm, humid
days. The adult flea is ready to feed as soon as it
leaves the cocoon.
Adult fleas live on the pet and in the pet's
The bite distribution pattern in dogs and cats
sleeping or resting area. Adult fleas are parasites --
begins across the hips near the tail and narrows along
they obtain their nourishment from a host animal,
the back. An area between the hind legs and on the
usually mammals. They feed by biting and sucking
belly can also be affected. Cats are less affected on the
blood, sometimes daily, for two or three weeks. Most
belly than dogs, but often have problems on the neck
feeding takes place while the pet is sleeping or at rest.
or collar. Once the allergy is activated, reaction is
Cat flea larvae cannot live without dried blood from
sudden with few subsequent bites. Flea allergy also
the adults, therefore fleas are not evenly distributed
seems to be hereditary.
throughout a home or building.
Module One, Chapter 7, Pg 2