T ATE pLkT BOARD
INSECTS IN RELATION
INSECTS IN RELATION
Circular 13 Fleas
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Table of Contents
Fleas of Continental United States.....*.......... 2
Fleas Occurring in Tropical America....**********........... 4
Outbuildings..... ..................... ........ .. 6
Living Quarters................................ 6
Treatment of DomesticAnimals................... 7
Control of RodentFleas......................... 7
Prevention of Spread of Fleas*..................******* 8
Treatment for Flea Bites: Prevention of Bites... 8
Wherever men and such animals as dogs, cats, and
rodents are concentrated, conditions are favorable for
the development of fleas. Camps and other locations,
including ships, where men congregate and where pet and
stray dogs and cats occur, or where rats and mice forage
in storerooms, provide ideal conditions in which flea
populations increase. Fleas annoy man by biting and
transmit serious diseases.
Circular 13 Fleas
Bubonic plague and endemic typhus are transmitted
to man by fleas. Plague among wild rodents has spread
eastward from the Pacific Coast until ten far western
states harbor natural reservoirs of this malady. The
fleas necessary to establish an outbreak of plague among
man may be transported in shipments of supplies or house-
hold goods by motor truck, railroad trains, ships, or
even airplanes. This applies also to endemic typhus
which is especially widespread in the southern states.
FLEAS OF CONTINENTAL UNITED STATES
Rodent fleas, capable of transmitting disease and
found associated with human habitations, are the Oriental
rat flea, Xenopsylla cheopis (Roths.); the European rat
flea, Nosopsyllus fasciatus (Bosc.) (fig. 1); and the
mouse (and ratT) flea, Ctenopsyllus segnis (Schon.).
Figure 1 The European rat flea, female
The Oriental rat
flea is potentially the
most dangerous of the
plague vectors. It is
the predominant rat flea
of warmer climates, occurs
in southern parts of the
United States, and is a
common flea on rats on
ships and in seaports. In
recent years it has appear-
ed at various points in the
interior of the United
States. The European rat
flea is a flea of cooler
climates. This rat flea
and the mouse flea are
throughout the country.
Both of the rat fleas may
transmit endemic typhus.
Many species of rodent fleas are capable of trans-
mitting plague, and under certain circumstances they bite
man; therefore, this danger should be considered, especial-
ly in areas where plague has been found among rodents.
Circular 15 Fleas
The principal fleas which annoy or bite man are:
the cat flea, Ctenocephalides felis (Bouche) (fig. 2);
the dog flea, Ctenocephalides canis (Curt.); and the
human flea, Pulex irri tans (L. Tfig. 3).
Figure 2 Cat flea, female
Figure 3 Human flea, female
Cat and dog fleas breed on cats and dogs alike,
and,when numerous or in the absence of the natural hosts,
attack man. They breed on various other animals also.
The cat and dog fleas are abundant in the eastern part of
the United States, but are relatively scarce in the West.
Human fleas attack man as well as dogs, cats, hogs,
and other animals. They are annoying in buildings, stables,
and surrounding premises, especially in the Middle West,
South, and on the Pacific Coast where this species is the
predominant one affecting man. It is chiefly important
because of its vicious bite. In laboratory experiments it
has transmitted plague, and its possible importance in
this connection should not be overlooked.
Circular 13- Fleas
FLEAS OCCURRING IN TROPICAL AMERICA
The following fleas associated with man have been
reported from Panama: the eat flea, the human flea, the
Oriental rat flea, the European rat flea, and the mouse
flea. These same species are encountered on the Carib-
In sub-tropical and tropical America, an additional
pest is encountered. This is the chigoee" flea, known
scientifically as Tunga penetrans (L.). This should not
be confused with the North American "chigger" which is a
mite. The chigoe is responsible for ulcerated sores on
the soles of the feet, under toenails, and between the
toes. Other parts of the human body are occasionally at-
tacked. Domestic animals, especially hogs, are hosts and
serve as a source of human infestation.
It is reported that during the East African Campaign
in the last World War, this flea not only caused much suf-
fering, but considerable loss of man power, due to its
"Chigoe" control includes ridding the premises of
fleas and eggs, and treating domestic animals as outlined
later in the case of other fleas. As a protection, shoes
should be worn. Chigoes are removed from the body with
a sterilized needle or knife-blade, and the open wound
treated with an antiseptic.
Because of the similarity in appearance and habits
of some of the species of fleas, it is impossible for any-
one but a specialist to determine definitely what species
are causing trouble. A specific identification may be
obtained by sending specimens to the Bureau of Entomology
and Plant Quarantine, Department of Agriculture, Washington,
D. C. Fleas should be dropped in vials containing 70%
(ordinary rubbing) alcohol and forwarded with the name of
the collector, place and date of collection, and host from
Circular 13 Fleas 5
For breeding, all fleas must have access to warm-
blooded animals. Adult fleas lay their eggs in the fur
and feathers of the animal host. These eggs drop off and
lodge in the sleeping quarters of the animal, or in cracks
in floors, out-of-doors on the ground, etc. The eggs
hatch in a few days into larvae (fig. 4) small worm-
like creatures which subsist on the debris found on the
floor or ground. In two weeks or more the larvae become
full-grown and enclose themselves in tiny cocoons (fig. 5)
in which they transform to adult fleas in the course of
a few days or longer. When the adult stage is reached,
the new crop of fleas apparently "born hungry" become
quite active in search of food, although they may subsist
for weeks without nourishment.
*. 4 ..,,- No i
Figure 4 Plea larva Figure 5 Plea cocoon
"Sand-flea" infestations are due to fleas hatched
from eggs dropped from cats or dogs. The animals may have
been away from the premises for a month or two, but the
flea eggs remain to complete development. Consequently,
when a person enters a cellar, vacant building, or yard,
he is besieged by hundreds of voracious fleas which ap-
parently have bred in the dust or sand.
The life history of the chigoe flea is an exception
to that of the usual flea, and is discussed here with con-
trol measures to avoid confusion with other species. The
female attaches herself firmly by means of her mouthparts
to the skin of the host. Consequent irritation causes a
swelling which envelops the insect except for a tiny open-
ing where the tip of the abdomen is exposed. Through this
Circular 13 Fleas
opening the flea obtains air and extrudes eggs which
drop to the ground or remain within the swelling. After
oviposition the female remains to cause continued in-
fection. Serious results may follow when several
chigoes penetrate in close proximity to one another.
Rodent fleas breed in the nests and burrows of
their hosts, and the adult fleas are often present in
great numbers on these hosts, but they also occur in and
about the burrows.
To effectually combat fleas, it is essential to
determine the source of the infestation, to treat or
destroy the animal host, and to destroy the immature
stages in the dust on floors or in the burrows of rodents.
To clean up an infestation of fleas in buildings,
nothing is better than a light spraying of creosote oil
without dilution. This substance, however, is strongly
odorous and will burn animals and plants, stain painted
surfaces, and damage prepared foods. Its use is recom-
mended where these properties are not important considera-
tions. It may be used in such situations as basements,
warehouses, outbuildings, dog kennels, and beneath build-
ings. A compressed-air sprayer or a bucket pump (see
Cir. 20) with a lead of high-pressure hose with tight
connections is the most satisfactory device for applying
For the control of fleas in living quarters the
use of flake naphthalene is advised. In dwelling houses,
about 5 pounds should be scattered over the floor of each
room. Treated rooms should be left closed for at least
24 hours. If desired, one room may be treated at a time,
then the naphthalene may be swept up and used in another
room. The amount of this material to be used in extra-
ordinarily large rooms should be in the same proportion
Circular 13 Fleaa 7
as given above. In any case the floors should be suf-
ficiently well covered to make them white in appearance.
Where cats have been sleeping on overstuffed furniture
these pieces should be covered with the naphthalene.
Where there are only a few scattered fleas in quarters
these may be killed by a commercial fly spray applied
with a spray gun.
Treatment of Domestic Animals
In addition to the treatment of premises as de-
scribed above, attention should be given to dogs, cats
or other animals which may serve as flea hosts. Often
infestations arise from stray animals gaining access to
certain parts of buildings. Therefore, all windows, ven-
tilators, etc., should be checked to see that they are
closed with glass, screens or otherwise. In the case of
animals kept in quarters, treatments of the individual
animal with derris or cube powder should be carried out
systematically, usually every two weeks.
A small amount of derris powder (a level teaspoon-
ful for a large dog) should be placed next to the skin
along the back and neck and on top of the head. For
smaller animals the amount should be reduced according to
size. Care should be taken not to overdose cats, especial-
ly the long-haired breeds, as licking this material from
the coat may cause illness. In fact, since the effective-
ness of derris is largely dependent upon the amount of
rotenone it contains, and much of the derris now on the
market contains a comparatively high rotenone content,
this material for use on cats may be safely diluted with
talcum powder in the proportion of 1 part derris to about
4 of talcum. An ordinary salt cellar will be found useful
in applying the powder as the hair is parted with one hand.
This treatment should be repeated at intervals of 2 weeks
where the animals have free run in order to prevent rein-
festation of living quarters.
Control of Rodent Fleas
Rat fleas are most effectively combated by destroy-
ing the rats and mice with poison baits, traps, or by
fumigation with hydrocyanic acid gas or methyl bromide
(see Cir. 22). Since these fumigants are dan erous to man
they should be used only by a trained, experienced operator.
Circular 13 Pleas
Spraying the nests and runs with creosote oil will de-
stroy the fleas actually struck. Of course, if a proper
fumigation is carried out for rat control, all fleas
will be destroyed in the building, but spraying may be
necessary beneath the building or in other places where
the full charge of gas does not reach.
Methyl bromide is an effective insecticide and
rodenticide. It kills rodents and the fleas whether on
them or in the burrows. Methyl bromide is noninflammable
and is effective in wet or dry soils at various tempera-
tures. However, because it is odorless and colorless,
apt to cause burns and dermatitis by careless handling,
and rather high in price, this fumigant is not recom-
mended generally. Personnel should be trained in its use
and should function only under competent supervision.
Grains and similar cargoes may be treated for fleas with
this fumigant without rendering the food-unfit for human
consumption. Rat burrows may be effectively fumigated
and all stages of fleas from eggs to adults killed. The
dosage of methyl bromide recommended for ground squirrels
is 10 cc. per burrow. Applicators consist of small steel
cylinders equipped with a measuring device.
Prevention of Spread of Fleas
Transportation of fleas should be prevented as far
as possible. Household effects may harbor these pests in
all stages, especially as immature forms in rugs and
furniture. Fleas may be transported among mail sacks or
other materials used by animals for beds. Persons carry-
ing infested clothing or bedding may spread fleas. Motor
trucks, railroad trains, airplanes, and ships must there-
fore be considered in combating fleas.
Thorough cleaning and, when necessary, spraying
and fumigation of conveyances are recommended. On ships
where men are housed as well as transported, living quarters
and pets should be treated in accordance with measures al-
ready given, and rats should be exterminated by fumigation
and excluded at ports by the use of effective rat guards.
Treatment for Flea Bites: Prevention of Bites
Individuals differ considerably in their reactions
to flea bites. In some cases the irritation is slight and
STATE PLANT BOARD
Ciroular 3IS eaa
may be forgotten quickly. In others it persists and if
the bites are numerous considerable discomfort may re-
sult. In any case, the site of the bite should not be
scratched as this may lead to infection. Cooling lotions
usually give relief. Among the applications which have
been recommended are: mentholated ointments, spirits of
camphor, carbolated vaseline, and hydrogen peroxide.
Fresh pyrethrum powder is repellent to fleas and
may be sprinkled on the underwear and socks and on the
bedding when there appears to be danger of being bitten.
Cots or beds may be isolated from fleas by setting
the legs in tin covers containing water or a little
kerosene and by exercising care not to let the bedding
get near the floor.
Bishopp, F. C. ----- 1931 Fleas and Their Control.
Farmers' Bull. 897, U.S.
Dept. of Agriculture, Bur.
of Entomology, Div. of In-
sects Affecting Man and
Animals, Washington, D. C.
Dyer, R. E., ----- 1932 -- Endemic Typhus of the United
Ceder, B. T., States. Jour. Infect. Dis-
Rumreich A., and eases 51(1):137-161.
Badger, L. F.
Fox, Carroll and --- 1925 A Comparative Study of Rat-
Sullivan, B. C. Flea Data for Several Sea-
ports of the United States.
Pub. Health Repts. 40(37):
Fox, Irving --- 1940 -- Fleas of Eastern United States.
Iowa State College Press,
Ames, Iowa, 191 pp.
Jennings, A. H. -- 1910 -- Rats and Fleas in Relation to
Bubonic Plague (with Special
Reference to Panama and the
Canal Zone). Paper read at
a meeting of the Med. Assoc.
of the Isthmian Canal Zone.
I.C.C. Press. Quartermaster's
Dept. Mt. Hope, C. Z.
Circular 13 Fleas 10
Patton, Walter Scott -- 1929 -- Insects, Ticks, Mites and
and Evans, A. M. Venomous Animals of
Medical and Veterinary
Importance, Part I -
Medical. H. R. Grubb Ltd.,
Russell, Harold ------- 1913- The Flea. G.P.Putnam's
Sons, New York. 125 pp.
Silver, James --------- 1927 Rat Control. Farmers' Bull.
No. 1533, U. S. Dept. of
Agriculture, Bur. of
Biological Survey, Div. of
Predatory-Animal and Rodent
Control, Washington, D. C.
Stewart, M. A. and ---- 1938 The Control of Sylvatic
Mackie, D. B. Plague Vectors. Amer.
Jour. Hyg. 28(3): 469-480.
Trembley, Helen Louise- 1940 Distribution and Hosts of
and Bishopp, F. C. Some Fleas of Economic
Importance. Jour. Econ.
Ent. 33(4): 701-703.
UNIVERSITY OF FLORIDA
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