Insects in relation to national defense


Material Information

Insects in relation to national defense
Series Title:
Its Circular no. 1-23. Feb. 1941-Jan. 1944
Added title page title:
Insects in relation to national defense, circular
Physical Description:
24 nos. in 1 v. : ill., photos., map, plans, diagrs. ; 23 cm.
United States -- Bureau of Entomology and Plant Quarantine
U.S. Govt. Print. Off.
Place of Publication:
Publication Date:


Subjects / Keywords:
Beneficial insects   ( lcsh )
Insect pests   ( lcsh )
Insecticides   ( lcsh )
Fumigation   ( lcsh )
World War, 1939-1945 -- Health aspects   ( lcsh )
serial   ( sobekcm )
non-fiction   ( marcgt )


General Note:
Reproduced from type-written copy.
General Note:
Includes bibliographical references.

Record Information

Source Institution:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 029081698
oclc - 09471812
lcc - SB931 .U44
System ID:

Full Text




TO 0



Circular 17


May 1941



Circular 17 Stable Flies

Table of Contents
Introduction...*.........................*** i
Distribution....****. ......*.......**ge.. 2
Breeding Places....2...*......*........*.. 2
Description of Stages and Life Cycle......******** 3
Habits.................. ..........:.......... 5
Biting and Egg Laying.................... 5
Flight.. ..................................
Hibernation.********..............................*** 6
Control...........***............***.*...... 7
Prevention of Breeding.................... 7
Treatment of Infested Material.... *..... 8
Manure.............* ..**.** *.....o...... 8
Straw............... ........* ... *........
Bay grasses..g.........***............. 8
Other breeding materials................ 9
Fly Sprays .............................. 9
Traps..........................*........*** i0
References...*.*.*.** ...* ... * * .* * **** 12


The stable fly, or dog fly (Stomoxys cal-
citrans L.), is widely distributed in various
parts of the world. It is a vicious blood sucker,
the bite of which produces severe pain.

Circular 17 Stable Flies 2

This fly has been shown to be capable of
carrying a number of diseases of livestock, such
as anthrax, surra, and swamp fever, and one exper-
iment indicated that it can carry infantile par-

The most important role of the fly, however,
is annoyer of man and animals. When present in
outbreak numbers, as is not infrequent in the
grain belt and along the East Coast, especially
in western Florida, it may kill horses and cattle
by continuous worry and loss of blood, drive people
away from the beaches, and prevent effective per-
formance of activities in all places where they
are exposed to free attack. Under such condi-
tions it is difficult to control horses, and their
condition and work efficiency are materially low-
ered. Production of dairy herds is often decreased
from 5 to 25 percent, and the ears and other parts
of dogs and hogs are made raw by the flies' numer-
ous punctures.


As indicated in the introduction, the stable
fly is widely distributed. It is present in all
parts of the United States, Mexico, and the West
Indies. It is usually most troublesome in the
grain belt from north Texas to North Dakota and
Minnesota. It is also extremely abundant along
the coast of the Gulf of Mexico from Pensacola to
Carrabelle, Florida. Severe local outbreaks may
occur in any part of the country where conditions
are.favorable for it to breed.


Stable flies breed in fermenting vegetable
matter of many kinds. Manure, especially horse
manure mixed with straw or other bedding material,
is a common breeding place. Straw stacks which

Circular 17 Stable Flies

become wet soon after threshing have been known
to produce hordes of these flies. Oat straw,
especially when mixed with grain and chaff, is
very favorable as a breeding place. Corn husks,
corn cobs, hay, and other materials wasted around
feed racks and wet by manure, urine, and rain
produce large numbers of flies. Lawn clippings
and accumulations of weeds piled up and allowed
to ferment are also suitable breeding places
for this fly. Weeds, grass, and other debris
washed up by heavy rains or by floods may also
become infested.

Along the coast, especially on the shores
of bays in western Florida, drifts of marine
grasses, when washed high on the beaches where
they are not frequently reached by tides, have
been found to breed large numbers of these
flies. It appears that these windows of grasses
are responsible for the serious outbreaks of
the stable, or dog, fly in that region. This
insect has also been found to develop in great
numbers in peanut litter left in fields after
peanuts have been threshed. There is some indi-
cation that part of the trouble on the beaches
may be due to these inland breeding places.


The stable fly resembles the common house-
fly. It is slightly more robust and has a
strong piercing beak which can be seen pro-
jecting forward beneath the head when thG
fly is at rest, Fig. 1. The elongate, whit-
ish eggs are laid in loose masses on ferment-
ing vegetable matter. These hatch in 1 to 3
days into minute whitish maggots that feed on
the moist material usually near the surface.

Circular 17 Stable Flies

They attain full size, Fig. 2, about 4/5 of
an inch in length, in 7 to 30 days, or even
longer in cold
weather. The mag-
*got changes into
vthe pupa, or rest-
ing stage, in the
breeding material
V or in the soil
nearby. The pupa
is yellowish at
B f ~ first, later chang-
Ss ing to dark brown
S/ \ or nearly black.
/ In form it is some-
". what barrel-shaped,
as is usual with
S.. flies of this fam-
ily, Fig. 3. This
stage lasts about
6 to 20 days. The
Figure 1 The stable fly. fly pushes the head
end of the hard
pupa case open and
crawls out. It
soon spreads its wings and after its body
hardens, it is ready to fly and seek an animal
upon which
to feed.
Eggs are
..... not laid for
f T 111 aip. '3 or 4 days
after emer-
....Senee. The
life cycle
may be com-
pleted in
Figure 2 Larva, or maggot. 18 days,
but it usu-
ally requires 21 days and may take three months
during cool weather.

Circular 17 Stable Flies


Biting and Egg Laying

Both sexes of the stable fly are blood
suckers. The flies have a strong tendency to
bite on the lower parts of the legs of both
man and animals. On horses and cattle the
outside of the forelegs
is preferred, but when
-numerous the flies attack
any part of the animal,
Especially the shoulders,
sides, and neck.

The flies insert
their beaks very quickly
Figure 3- Pupa. after alighting and
they are ready to fly
away quickly when dis-
turbed. They may become fully fed in 2 to 5
minutes when not disturbed. Usually, however,
they are disturbed and make many punctures
and perhaps bite several different animals or
people before they are satisfied. This repeated
attack on a number of different animals or
people would appear to favor the transmission
of disease. Considerable blood is drawn;
frequently the flies become so full of blood
they can scarcely fly, Fig. 4. When fed they
fly to nearby buildings, fences, or trees, and
there rest while digesting their meal.

Usually the flies feed on blood every
day or even twice a day during hot weather.
They also suck up moisture from the breeding
material or from leaves. In cold weather they
may not bite for several days. When it warms
up they are especially vicious. During the
life of a fly, from 3 to 5 masses of eggs rang-
ing from a few to more than 100 are deposited

Circular 17 Stable Flies

with one or more blood meals interspersed.

Horses and cattle are preferred over
man as hosts, out large animals of all kinds
are attacked, and cold-blooded animals may
occasionally be bitten.


The stable fly is a swift and strong
flier. The species has been observed to fol-
low animals for considerable distances, mak-

r- ^ -- -

Figure 4 Adult female,

ing repeated efforts to
dence that this fly may
as it has been observed
on boats many miles off
have been recaptured 52

engorged with blood.

bite. There is evi-
travel long distances
to appear in numbers
shore. "Marked" flies
miles from point of


In cold climates the stable fly passes
the winter in the larval or pupal stages,
development usually proceeding slowly. In the
warmer parts of the world breeding is continu-



Circular 17 Stable Flies

ous the year around. In the Southern States
flies continue to emerge during warm periods
in winter. Ordinarily these flies die without
laying eggs, but those which do not emerge
untilfavorable temperatures occur in spring
deposit eggs and breeding continues.

The elimination of breeding places is
of paramount importance in controlling the
stable fly. Many of the control procedures
recommended for the housefly (Circular No. 8;
are of value in combating tne stable fly.
Prevention of Breeding
Breeding of the stable fly may be pre-
vented largely by proper handling of manure,
straw, peanut litter, grass clippings, and
other vegetable matter that may ferment. Since
this fly breeds in a large variety of farm
wastes, most of which are beyond the juris-
diction of the defense agency that may be ad-
versely affected by the fly, cooperation of
farmers and other civilian populations in the
area must be secured.
Straw should be well stacked as grain
is threshed so as to prevent the rains from
soaking deeply into it, or the straw should
be baled at once and stored in a dry place.
The butts of straw stacks should be scattered
thinly on fields. This is particularly true
of the chaff and light grain mixed with it,
As stable flies may breed in shocked grain
exposed to rain for considerable periods,
prompt threshing is desirable.

J 6'6

Circular 17 Stable Flies

In general, the treatments given below
for infested materials are effective in pre-
venting initial infestations.

Treatment of Infested Material

Manure.--Prompt scattering on fields
or ricking and composting of manure, as described
for the control of the housefly (Circular 8;
is recommended when large quantities must be
cared for. The use of manure pits and of borax
(Circular 8) is applicable to stable fly control
in smaller lots of manure held for fertilizing

Manure, hay, and other vegetable mater-
ials scattered around feed racks must be cleaned
up every 3 or 4 days and treated as above if
fly breeding therein is to be prevented.

Sludge, either while floating on sewage
disposal tanks or being dried on sludge beds,
may breed great numbers of stable flies if
not treated. The floating material should
be submerged mechanically and the sludge on
drying beds either sprinkled with borax or
scattered thinly so as to hasten drying.

Straw.--TWhen straw stacks have become
thoroughly wet by heavy rains soon after thresh-
ing and fly breeding is taking place in them,
it is advisable to burn them at once if the
straw is not urgently needed for other purposes.
Scattering the straw thinly over fields with a
straw spreader or by hand will check breeding.

Bay grasses.--The development of large
quantities of these flies in windows of bay
grasses washed up on certain types of beaches
along the Gulf Coast by tides and storms has

Circular 17 Stable Flies

been discovered only recently. Measures for
control under these conditions have not been
fully developed or tested.

Preliminary control experiments indicate
that applying a mixture of creosote oil, 1
part, and fuel oil No. 2, 3 parts, sprayed
into the windows of bay grasses with a power
sprayer (Circular No. 22), using 300-pound
pressure, has given promising results. This
method of control is described in Circular
E-541, "Control of Dog Fly Breeding in Beach
Deposits of Marine Grasses" (see list of ref-
erences), which will be supplied on request
together with any new facts that are developed
by studies now under way.

Other breeding materials.--Stable fly
breeding in peanut litter, grass clippings,
ensilage, and other wet fermenting vegetable
materials is best controlled by scattering
infested materials thinly on open fields.
This method of control is described in Cir-
cular E-542, "Control of Dog Fly Breeding
in Peanut Litter" (see list of references).

Fly Sprays

Stable flies are much more easily killed
by pyrethrum-oil sprays (Circular 21) than
are houseflies and most other insects. The
main difficulty is to reach them with the
spray, for, as previously stated, they are
present on livestock a short time and rest
most of the time on objects away from their

Spraying livestock lightly with pyre-
thrum concentrates containing 5 to 10 parts
of the concentrate to 1 part of light, highly
refined oil (see Circular 21) kills the flies

Circular 17 Stable Flies

hit by the spray. When thus used the poison-
ous effect of the pyrethrum persists on the
hair for several hours and stuns or kills the
flies that attempt to feed. Pyrethrum oil
spray of the usual strength (1 to 1) is effec-
tive in killing the flies which may be found
in mess halls, barns, or other buildings.

No material has been found that is
highly effective in repelling stable flies
from livestock or people for any length of


Ordinary conical fly traps (see Circu-
lar 20) catch very few stable flies because
these flies are not strongly attracted to

Hodge traps, Fig. 5, set in windows
of barns in which livestock is kept catch
considerable numbers of these insects as
they attempt to enter or leave the barn.
They are most effective if the buildings
are fairly tight and the windows not provided
with traps are darkened with burlap or other

Electric grids (see Circular 20) set
in windows in the same way also kill consid-
erable numbers of these flies.

Traps, however, are only minor supple-
ments to the treatment of breeding places.

Circular 17 Stable Flies


Figure 5 Hodge trap in window of barn: A. door
for removing dead flies; B. screen bent into
V-shaped folds and provided with quarter-inch
holes C. along apex to catch flies trying to
enter barn; D. folds on opposite side to admit
flies trying to leave barn; E. hinges on door.

Circular 17 Stable Flies


Bishopp, F. C. --------- 1931 -- The Stable Fly:
How to Prevent
Its Annoyance
and Its Losses
to Livestock.
Farmers' Bull.
No. 1097, U. S.
Dept. of Agri-
culture, Bur-
eau of Entomol-
Dove, W. E. and ----- 1941 Control of Dog
Simmons, S. W. Fly Breeding
in Peanut
Litter. Cir-
cular E-542,
U. S. Dept. of
Bureau of Ento-
mology and
Plant Quaran-
Simmons, S. W. and --- 1941 Control of Dog
Dove, W. E. Fly Breeding
in Beach Depos-
its of Marine
Grasses. Cir-
cular E-541,
U. S. Dept. of
Bureau of Ento-
mology and
Plant Quaran-

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