Produced by Tom Cosmas from files generously made available
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Transcriber Note

Text emphasis denoted as _Italics_ and =Bold=. Whole and fractional parts
of numbers as 123-4/5.



                      =FLYTRAPS AND THEIR OPERATION=


                              F. C. BISHOPP

          Entomologist, Investigations of Insects Affecting the
                            Health of Animals


                              [Illustration]


                          FARMERS' BULLETIN 734

                 UNITED STATES DEPARTMENT OF AGRICULTURE



                Contribution from the Bureau of Entomology
                           L. O. HOWARD, Chief



 Washington, D. C.   Issued June 10, 1916; second revision, March, 1921.


Show this bulletin to a neighbor. Additional copies may be obtained free
from the Division of Publications, United States Department of Agriculture


              WASHINGTON : GOVERNMENT PRINTING OFFICE : 1921


RESULTS obtained in experiments with the use of chemicals against fly
larvæ in manure are presented in Bulletins Nos. 118, 245, and 408 of the
Department of Agriculture. The biology of the house fly and the various
methods of control are discussed in Farmers' Bulletin 851.

This bulletin is intended to give directions for the use of a
supplementary means of controlling flies. It is adapted to all parts of
the United States.




=FLYTRAPS AND THEIR OPERATION.=




=CONTENTS.=


                                              Page.

  Uses and limitations of flytraps               3

  Kinds of flies caught                          3

  Types of traps                                 4

  Trapping the screw-worm fly                   13

  Baits for traps                               13

  Bait containers                               15

  Care and location of traps                    15

  Sticky fly papers                             16

  Poisoned baits                                16

      Caution                                   16




=USES AND LIMITATIONS OF FLYTRAPS.=


FLYTRAPS have a distinct place in the control of the house fly and other
noxious fly species. There is a general tendency, however, for those
engaged in combating flies to put too much dependence on the flytrap
as a method of abating the nuisance. It should be borne in mind that
flytrapping is only supplementary to other methods of control, most
notable of which is the prevention of breeding either by completely
disposing of breeding places or by treating the breeding material with
chemicals.

It may be said that there are two main ways in which flytraps are
valuable: (1) By catching flies which come to clean premises from
other places which are insanitary and (2) by capturing those flies
which invariably escape in greater or less numbers the other means of
destruction which may be practiced. Furthermore, the number of flies
caught in traps serves as an index of the effectiveness of campaigns
against breeding places.

_Flytrapping should begin early in the spring if it is to be of greatest
value._ Although comparatively few flies are caught in the early spring,
their destruction means the prevention of the development of myriads of
flies by midsummer.




=KINDS OF FLIES CAUGHT.=


The various species of flies which are commonly annoying about habitations
or where foodstuffs are being prepared may be divided roughly into two
classes: (1) Those which breed in animal matter, consisting mainly of the
so-called blowflies, including the screw-worm fly;[1] and (2) those which
breed in vegetable as well as in animal matter. In the latter group the
house fly[2] is by far the most important. The stable fly is strictly a
vegetable breeder, as are also certain other species which occasionally
come into houses and in rare cases may contaminate foodstuffs. The stable
fly,[3] which breeds in cow manure or decaying vegetable matter, and the
horn fly,[4] which breeds in manure, are blood-sucking species, and can be
caught in ordinary flytraps in comparatively small numbers only. The kind
of flies caught depends to a considerable extent on the material used for
bait. In general the house fly and other species which breed in vegetable
matter are attracted to vegetable substances, while the blowflies will
come most readily to animal matter. This rule, of course, is not absolute,
as flies are less restricted in feeding than in breeding habits, and, as
is well known, the house fly is attracted to a greater or less extent to
any moist material, especially if it has an odor.

[1] _Chrysomyia macellaria_ Pab.

[2] _Musca domestica_ L.

[3] _Stomoxys calcitrans_ L.

[4] _Lyperosia irritans_ L.




=TYPES OF TRAPS.=


The same general principle is involved in nearly all flytraps in use,
though superficially they may appear quite different. The flies are
attracted into a cage, as it were, by going through a passage the entrance
of which is large and the exit small, so that there is little chance
of the flies, once in, finding their way out again. This principle is
modified to fit different conditions. For instance, the window trap,
devised by Prof. C. F. Hodge, catches the flies as they endeavor to enter
or leave a building; the garbage-can trap, for which Prof. Hodge is also
to be credited, catches the flies that have entered garbage cans; and the
manure-box trap retains the flies bred from infested manure put into the
box.

The attractant used to induce flies to enter traps may consist of (1)
food, as in baited traps; (2) odors, as in window traps placed in windows
from which odors are emitted; and (3) light, as in traps on manure boxes.
Of course, light is an important factor in the success of all traps, for,
as is well known, flies have a marked tendency to go toward the light, and
they usually enter the trap by flying toward the light after having been
attracted beneath it by bait or after entering a room in search of food.


=CONICAL TRAPS.=

A number of traps of this general type are on the market, but most of
these are of small size. Nearly all are constructed with a dome instead of
a cone, and on this account the catching power is reduced about one-third.
Moreover, the farmer, dairyman, or anyone with a few tools can construct
traps at a small fraction of the sale price of ready-made ones.


=THE CONICAL HOOP TRAP.=

A trap which appears from extensive tests made by Mr. E. W. Laake and the
author to be best for effective trapping, durability, ease of construction
and repair, and cheapness may be made as follows:

[Illustration: Fig. 1.--Conical hoop flytrap, side view. _A_, Hoops
forming frame at bottom. _B_, Hoops forming frame at top. _C_, Top of trap
made of barrel head. _D_, Strips around door. _E_, Door frame. _F_, Screen
on door. _G_, Buttons holding door. _H_, Screen on outside of trap. _I_,
Strips on side of trap between hoops. _J_, Tips of these strips projecting
to form legs, _K_. Cone. _L_, United edges of screen forming cone. _M_,
Aperture at apex of cone.]

The trap consists essentially of a screen cylinder with a frame made of
barrel hoops, in the bottom of which is inserted a screen cone. The height
of the cylinder is 24 inches, the diameter 18 inches, and the cone is 22
inches high, and 18 inches in diameter at the base. Material necessary
for this trap consists of four new or secondhand wooden barrel hoops, one
barrel head, four laths, 10 feet of strips 1 to 1½ inches wide by one-half
inch thick (portions of old boxes will suffice), 61 linear inches of 12
or 14 mesh galvanized screening 24 inches wide for the sides of the trap
and 41 inches of screening 26 inches wide for the cone and door, an ounce
of carpet tacks, and two turn-buttons, which may be made of wood. The
total cost of the material for this trap, if all is bought new at retail
prices, is about $1. In practically all cases, however, the barrel hoops,
barrel head, lath, and strips can be obtained without expense. This would
reduce the cost to that of the wire and tacks, which would be 80 cents.
If a larger number of traps are constructed at one time, the cost is
considerably reduced.

One of these traps is illustrated in figures 1 and 2. In constructing the
trap two of the hoops are bent in a circle (18 inches in diameter on the
inside), and nailed together, the ends being trimmed to give a close fit.
These form the bottom of the frame (_A_), and the other two, prepared in
a similar way, the top (_B_). The top (_C_) of the trap is made of an
ordinary barrel head with the bevel edge sawed off sufficiently to cause
the head to fit closely in the hoops and allow secure nailing. A square,
10 inches on the side, is cut out of the center of the top to form a door.
The portions of the top (barrel head) are held together by inch strips
(_D_) placed around the opening one-half inch from the edge to form a
jamb for the door. The door consists of a narrow frame (_E_) covered with
screen (_F_) well fitted to the trap and held in place (not hinged) by
buttons (_G_). The top is then nailed in the upper hoops and the sides
(_H_) formed by closely tacking screen wire on the outside of the hoops.
Four laths (_I_) (or light strips) are nailed to the hoops on the outside
of the trap to act as supports between the hoops, and the ends are allowed
to project 1 inch at the bottom to form legs (_J_). The cone (_K_) is cut
from the screen and either sewed with fine wire or soldered where the
edges meet at (_L_), or a narrow lath may be nailed along these edges.
The apex of the cone is then cut off to give an aperture (_M_) 1 inch in
diameter. It is then inserted in the trap and closely tacked to the hoop
around the base.

[Illustration: Fig. 2.--Conical hoop flytrap, top view. Letters designate
parts as in figure 1.]

The construction of a cone of any given height or diameter is quite simple
if the following method be observed. It is best to cut a pattern from a
large piece of heavy paper, cardboard, or tin, Figure 3 illustrates the
method of laying out a cone of the proper dimensions for the above trap.
An ordinary square is placed on the material from which the pattern is to
be cut; a distance (22 inches) equal to the height of the cone is laid
off on one leg of the square at _A_, and a distance (9 inches) equal to
one-half of the diameter of the base of the cone is laid off on the other
leg at _B_, and a line is drawn between the points _A_ and _B_. With the
distance between these points as a radius and with the point _A_ as a
center, the portion of a circle, _C D_, is drawn. With a pair of dividers,
the legs of which are set 1 inch apart, or with the square, lay off as
many inches on the arc _C D_, starting at _C_, as there are inches around
the base of the cone, which in this case is about 56½ inches, reaching
nearly to the point _E_. Then add one-half inch for the lapping of the
edges of the cone, and one-half inch which is taken up when the cone is
tacked in, thus making a total distance from _C_ to _E_ of 57½ inches.
Draw a line from _A_ to _C_ and another from _A_ to _E_, and cut out the
pattern on these lines and on the arc from _C_ to as shown in figure
3. The edges _AC_ and _AE_ are then brought together, lapped one-half
inch, and sewed with wire or soldered. After the aperture of the cone is
formed by cutting off the apex, as previously described, it is ready for
insertion in the trap.

[Illustration: Fig. 3.--Method of laying out a pattern for the
construction of a cone. Cut out on curved line _C_ to _E_ and on dotted
lines from _A_ to _C_ and _A_ to _E_.]

In order to figure the distance around the base of a cone of any given
diameter multiply the diameter by 3.1416 or 3-1/7.

The height of the legs of the trap, the height of the cone, and the size
of the aperture in the top of the cone, each are of importance in securing
the greatest efficiency.


=OTHER FORMS OF CONICAL TRAPS.=

A modification of the previously described trap has been made by Mr. D. C.
Parman of the Bureau of Entomology. The principal point of advantage in
this type is that it can be made more quickly and with fewer tools. The
principles and dimensions are the same, the most striking difference being
the absence of a wooden top. A single hoop with the thick edge down forms
the upper frame of the cylinder and the entire top is made of screen.
A circular piece of screen with a diameter about 3 inches greater than
the diameter of the cylinder is cut; a hoop with a diameter equal to the
inside of the top of the trap is then made of heavy wire and laid upon the
disk of screen and the edges of the screen bent in over it. By folding in
and crimping the edges of the wire over the wire hoop it will remain in
position without difficulty and the edges of the screen disk are used to
lift the top of the trap out for emptying flies. It is important to have
the screen top fit the inside of the cylinder very snugly at all points.
If there is any space left where flies can escape it is a good plan to
bind the edge of the top with a strip of burlap. This not only helps
to close the openings but keeps the hoop in place and aids in removing
the top. Another difference is that the screen forming the sides of the
cylinder is placed on the inside of the hoops and legs, the frame being
built first and then the cylinder formed by tacking the wire on the inside
of the hoops and nailing in along the upright strips and against the wire
short pieces of laths with their upper ends against the lower edge of the
hoop forming the top of the trap and extending downward along the legs
about two-thirds of their length. These strips hold the wire in place and
give rigidity to the trap, and they are thick enough to project beyond the
inner surface of the hoop and form a support upon which the edges of the
screen top rest.

[Illustration: Fig. 4.--Tent flytrap. When the trap is set up the screen
box. _A_, fits on the base, _B_, and two pans of bait are placed beneath
the tent. _C_, Hole in screen at apex of tent.]

Conical traps with steel frames are satisfactory, but they are less easily
rescreened. These, of course, can be constructed only by shops with
considerable equipment. Traps constructed with a wooden disk about the
base of the cone, and a similar disk around the top to serve as a frame,
or those with a square wooden frame at the bottom and top, with strips up
the corners, are fairly satisfactory. It should be borne in mind that the
factor which determines the number of flies caught is the diameter of the
base of the cone, if other things are equal. Therefore the space taken up
by the wooden framework is largely wasted, and if it is too wide it will
have a deterrent effect on the flies which come toward the bait. For this
reason it is advisable that the wood around the base of the cone should be
as narrow as consistent with strength--usually about 3 inches.

_Under no condition should the sides or top of the trap be of solid
material_, as the elimination of light from the top or sides has been
found to decrease the catch from 50 to 75 per cent.


=TENT TRAPS.=

The tent form of trap has been widely advocated in this country, but
recent experiments indicate that it is much less efficient than the cone
trap, and usually as difficult to construct and almost as expensive. The
size of these traps may vary considerably, but one constructed according
to the dimensions given in figure 4 will be found most convenient. The
height of the tent should be about equal to the width of the base, and the
holes (_C_) along the apex of the tent should be one-half to three-fourths
of an inch in diameter and 1 inch apart. The box (_A_) should be provided
with hooks to pass through the eyes on the base (_B_). Small blocks 1 inch
thick are nailed beneath the corners of the tent frame to serve as legs.


=GARBAGE-CAN TRAPS.=

As previously mentioned. Prof. Hodge has adapted the cone trap to use on
the lids of garbage cans. It is not advisable to use this trap except
where garbage cans are sufficiently open to admit flies. In such cases a
hole may be cut in the lid of the can and one of the small balloon traps
which are obtainable on the market attached over the hole. To make the
trap effective the edges of this lid should extend well down over the top
of the can. The lid should be held up slightly so as to allow the flies
to pass under, but not high enough to admit direct light. Practically
speaking, the garbage forms the bait for this trap, and when inside the
can the flies are attracted to the light admitted through the trap. It
is really advisable to have the garbage cans fly proof, so as to prevent
danger of fly breeding within them rather than to depend on traps on the
lids, which necessarily allow odors to escape. A garbage can with a trap
attached is illustrated in figure 5.

[Illustration: Fig. 5.--Top of garbage can with small balloon flytrap
attached.]


=MANURE-BOX TRAPS.=

Manure pits or boxes are desirable for the temporary storage of manure,
especially in towns and cities. These have been widely advocated, but the
difficulty has been that manure often becomes infested before it is put
into them, and flies frequently breed out before the boxes are emptied and
often escape through the cracks. To obviate these difficulties a manure
box or pit, with a modified tent trap or cone trap attached, is desirable.
Mr. Arthur Swaim, of Florida, has devised a form of manure trap consisting
of a series of screen tents with exit holes along the ridges of these,
over which is a screen box. The latter retains the flies as they pass
through the holes in the tents. The entire trap is removable.

In order to retain the fertilizing value of manure to the greatest extent
it is advisable to exclude the air from it as much as possible and to
protect it from the leaching action of rains. This being the case, there
is really no necessity to cover a large portion of the top of the box with
a trap, but merely to have holes large enough to attract flies to the
light, and cover these holes with ordinary conical traps, with the legs
cut off, so the bottom of the trap will fit closely to the box. The same
arrangement can be made where manure is kept in a pit. In large bins two
or more holes covered with traps should be provided for the escape of the
flies.

Manure boxes should be used by all stock owners in towns and cities, and
they are also adaptable to farms. The size of the manure bin should be
governed by the individual needs, but for use on the farm it is desirable
to make it large enough to hold all of the manure produced during the
busiest season of the year. A box 14 feet long, 10 feet wide, and 4 feet
deep will hold the manure produced by two horses during about five months.
About 2 cubic feet of box space should be allowed for each horse per day.
The bin should be made of concrete or heavy plank. When the latter is used
the cracks should be battened to prevent the escape of flies. The bin may
have a floor or it may be set in the ground several inches and the dirt
closely banked around the outside. For the admission of the manure a
good-sized door should be provided in either end of a large bin. A portion
of the top should be made easily removable for convenience in emptying the
box, or one entire end of the box may be hinged. On account of the danger
of the door being left open through carelessness, it is advisable to
arrange a lift door which can be opened by placing the foot on a treadle
as the manure is shoveled in. The door should be heavy enough to close
automatically when the treadle is released. A manure bin with flytrap
attached is shown in figure 6.

[Illustration: Fig. 6.--Use of flytrap in connection with manure bin. _A_,
Block of wood set in ground to which lever raising door is hinged.]

Attention is directed to a maggot trap devised by Mr. R. H. Hutchison, as
described in Farmers' Bulletin 851 of the Department of Agriculture. Where
large quantities of manure are produced on a farm this method of storing
the manure on a platform and trapping the maggots which breed out may be
more convenient than the manure bin.


=WINDOW TRAPS.=

Prof. C. F. Hodge has designed a trap which is really a modified tent
trap adapted to use in a window. This trap is constructed so as to catch
the flies as they enter or leave through the window. It is adaptable to
barns which are fairly free from cracks or other places where flies may
enter. It may also be used on windows of buildings where foodstuffs are
prepared and where flies endeavor to enter through the windows or escape
after having gained entrance through other passageways. All openings not
provided with traps should be closely screened, and on large buildings
traps may be installed in every third window.

[Illustration: Fig. 7.--Hodge type window trap. At left, trap with end
removed to show construction; at right, cross section of trap placed in
a window. _A_, End of trap. _B_, Upper side of folds in screen. _C_,
Lower side of folds in screen. _D_, Portion of end of trap sawed out and
returned after attaching screen. _E_, Holes along apex of folds. _F_, Door
for removing dead flies. _G_, Window sill. _H_, Upper window sash. _I_,
Inside entrance for flies. _O_, Outside entrances.]

This trap is essentially a screen box closely fitted to the frame of a
window (see fig. 7). The thickness of the box at _A_ should be about 12
inches. Instead of the screen running straight down over the box on either
side it is folded inward nearly to the center of the frame in =V=-shaped
folds running longitudinally across the window. One, two, or even more
folds may be made in the screen on either side. The upper side of the fold
_B_ should extend toward the center almost at right angles with the side
of the trap--that is, parallel with the top and bottom; and the lower side
_C_ should slant downward as shown in the drawing. The sides of the frame
may be cut out at the proper angle and the pieces _D_ returned after the
screen has been tacked along the edges. Along the apex (inner edge) of
each fold is punched a series of holes _E_ about one-half inch in diameter
and 1 inch apart. The apices of the folds on either side of the window
should not be directly opposite. A narrow door _F_ opening downward on
hinges should be made on one side of the trap at the bottom for removal of
the dead flies. The entire trap is fastened to the window by hooks so that
it may be readily taken off. An additional trapping feature may be added
by providing a tent trap fitted in the bottom of the box. A narrow slit is
left along the base to allow the flies to enter beneath the tent. Bait
may be placed under the tent to attract the flies.

It has been found that the use of these window traps will aid in
protecting animals in barns from stable flies and mosquitoes, and in
some cases horseflies and other noxious species are caught. They tend to
exclude the light, however, and are somewhat cumbersome, especially in
thin-walled buildings.




=TRAPPING THE SCREW-WORM FLY.=[5]

[5] _Chrysomyia macellaria_ Fab.


Recent efforts to reduce the loss to the live-stock industry of the
Southwest resulting from the ravages of the screw-worm have directed
attention to the employment of flytraps in this work.

Mention has been made of the importance of preventing the breeding of
flies as a prerequisite to effective control. This is equally true of the
screw-worm and other blowflies, which attack animals, and of the house
fly. In the case of these blowflies main dependence must be placed on the
complete and prompt burning of all carcasses and animal refuse.

Experiments conducted in the range sections of Texas indicate that traps
properly baited and set are of material aid in preventing screw-worm
injury to live stock. It is advised that at least one trap be maintained
on each section of land. These should be located preferably near watering
places and where cattle congregate, especially in the so-called "hospital
traps," where the screw-worm-infested animals are kept for treatment.

The conical-type traps as described are advised. The traps should be set
on a board platform about 2 feet square, securely fastened to a tree or
on a post where the trap and bait will be the least disturbed by stock or
wild animals.

During the latter half of one season over 100 gallons of flies, the vast
majority of which were screw-worm flies, were captured in about 25 traps
operated on a ranch in west Texas.

The question of the baits best adapted for this species and other points
in regard to the operation of the traps are briefly discussed under
subsequent headings.




=BAITS FOR TRAPS.=


The problem of selecting the best bait for flies is an important one.
In choosing a bait it should be remembered that it is largely the
fermentation which renders the material attractive, and that baits are
most attractive during their most active period of fermentation. As has
been indicated, the kind of bait used should be governed by the species of
flies the destruction of which is desired. This is most often the house
fly.

Experiments conducted indicate that a mixture of cheap cane molasses
("black-strap") and water is among the most economical and effective baits
for the house fly. One part of molasses is mixed with three parts of
water. The attractiveness becomes marked on the second or third day.

Sugar-beet or "stock molasses," which is very cheap, especially in regions
where produced, when mixed in the foregoing proportions, is fairly
attractive.

On dairy farms, probably milk is the next choice as a bait to
cane-molasses solution, considering its convenience. The curd from milk,
with about one-half pound of brown sugar added to each pound and water
to make it thoroughly moist, is a very good bait and continues to be
attractive for 10 days or more if kept moist. A mash of bran made quite
thin with a mixture of equal parts of water and milk and with a few
tablespoonfuls of brown sugar and cornstarch and a yeast cake added makes
an attractive and lasting bait. During hot weather stirring the old bait
or adding fresh is a daily necessity if best results are to be secured.

Sirup made by dissolving 1 part of ordinary brown sugar in 4 parts
of water and allowing the mixture to stand a day or two to induce
fermentation is almost equal to the molasses and water as a fly bait. If
it is desirable to use the sirup immediately after making it, a small
amount of vinegar should be added. Honeybees are sometimes caught in
large numbers at this bait. When this happens some of the other baits
recommended should be used.

With the baits before mentioned comparatively few blowflies will be
caught. For use about slaughterhouses, butcher shops, and other places
where blowflies are troublesome, it has been determined that the mucous
membranes which form the lining of the intestines of cattle or hogs are
without equal as a bait. This material, which is commonly spoken of as
"gut slime," can be obtained from packing houses where sausage casings are
prepared. The offensive odor of this bait renders its use undesirable very
near habitations or materials intended for human consumption.

For use under range conditions experiments are underway with dried gut
slime. This material is giving satisfaction as a screw-worm fly attractant
and is easily carried, being in a highly concentrated form. The flaky
material is placed in the bait pans and water added at the rate of 1 part
slime to 10 or 20 parts water, after which the mixture is thoroughly
stirred.

Another packing-house product known as blood tankage is a good fly bait
when used with molasses and water. This combination results in the capture
of a large percentage of house flies. Where these materials are not
obtainable fairly good catches will result from the use of fish scraps
or meat scraps. With any of these baits the catches will be found not to
be entirely meat-infesting flies, as actual counts have shown that the
percentage of house flies in traps over such baits ranges from 45 to 75.

Overripe or fermenting fruit, such as watermelon rinds or crushed
bananas, placed in the bait pans sometimes gives satisfactory results.
A combination of overripe bananas with milk is much more attractive than
either one used separately. A considerable number of blowflies as well as
house flies are attracted to such baits.




=BAIT CONTAINERS.=


The size of the bait container in relation to the size of the trap is
a very important consideration. It has been found that a small pan
or deep pan of bait set in the center under a trap will catch only a
small fraction of the number of flies secured by using larger, shallow
containers. The best and most convenient pan for baits is a shallow
circular tin, such as the cover of a lard bucket. Under range conditions
it is advisable to use a more substantial bait pan and preferably one 1½
inches deep, so that a greater amount of bait may be used, thus preventing
complete drying out between visits to the trap. Its diameter should be
about 4 inches less than that of the base of the trap, thus bringing the
edge within 2 inches of the outside edge of the trap. For liquid baits
the catch can be increased slightly by placing a piece of sponge or a few
chips in the center of the bait pan to provide additional surface upon
which the flies may alight. The same kind of pans for bait may be used
under tent traps. Two or more pans should be used, according to the length
of the trap.




=CARE AND LOCATION OF TRAPS.=


In many cases flytrapping has been rendered ineffectual by the fact that
the traps were not properly cared for. In setting traps a location should
be chosen where flies naturally congregate. This is usually on the sunny
side of a building out of the wind. It is exceedingly important that the
bait containers be kept well filled. This usually requires attention
every other day. The bait pans should be washed out at rather frequent
intervals. This gives a larger catch and avoids the danger of flies
breeding in the material used for bait. Further, it should be borne in
mind that traps can not be operated successfully throughout the season
without emptying them. Where flies are abundant and the bait pans are
properly attended to the traps should be emptied at weekly intervals.
Where flies become piled high against the side of the cone the catching
power of the trap is considerably reduced. The destruction of the flies
is best accomplished by immersing the trap in hot water or, still better,
where a tight barrel is at hand place a few live coals in a pan on the
ground, scatter two tablespoonfuls of sulphur over them, place the trap
over the coals, and turn the barrel over the trap. All of the flies will
be rendered motionless in about five minutes. They may then be killed
by using hot water, throwing them into a fire, or burying them. In the
operation of flytraps in controlling the screw-worm it has not been found
necessary, especially during hot weather, to kill the flies, as they die
very rapidly within the traps. In order to empty a trap it may be inverted
and the dead flies shaken down. As the living flies will naturally go
upward, the door may then be removed and the dead flies shaken out, the
door replaced, and the trap set upright without loss of many of the living
flies.




=STICKY FLY PAPERS.=


Sticky fly papers are of some value in destroying flies which have
gained access to houses, but they have marked limitations and numerous
objectionable features. For use out of doors traps are much more effective
and economical.

Dr. Crumbine, of the Kansas State Board of Health, gives the following
method for preparing fly paper:

"Take 2 pounds of rosin and 1 pint of castor oil, heat together until it
looks like molasses. Take an ordinary paint brush and smear while hot on
any kind of paper--an old newspaper is good--and place several about the
room. A dozen of these may be made at a cost of 1 cent."




=POISONED BAITS.=


The question of destruction of flies with poisons is somewhat out of place
here, but the close relationship of poisoned baits to trapping warrants a
brief statement.

Probably the best poisoned bait for house flies is formaldehyde in milk
used at the rate of about two teaspoonfuls of formaldehyde to a pint of a
mixture of equal parts of milk and water. This is placed in flat dishes
in places frequented by flies. A piece of bread or a sponge in the dish
adds to the effectiveness. Brown sugar or molasses and water with 2½ per
cent formaldehyde (commercial, 40 per cent solution) added will probably
also give satisfactory results. As far as possible other liquids should be
removed when poisoned baits are exposed.

The use of poison solutions, especially arsenical solution in tubs
containing portions of animal carcasses, has been tried and advocated
against the screw-worm by a number of stockmen. A comparatively weak
poison solution--about 1 gallon of dip, diluted for use on cattle, to 7
gallons of water--is sufficient. Best results usually have been secured
where a considerable portion of the animal matter was allowed to protrude
from the poison solution, as there is a tendency for the solution
to harden the bait and prevent its decomposition, thus reducing its
attraction for flies.


=CAUTION.=

=It should be borne in mind that formaldehyde, 40 per cent, is poison
about in the same proportion as wood alcohol, if taken internally. It
should not be inhaled, nor should the eyes be unduly exposed to it.
Special pains should be taken to prevent children from drinking poisoned
baits and to prevent the poisoned flies from dropping into foods or
drinks. Arsenical solutions, as is well known, are extremely poisonous to
man and animals. Care should be taken to protect the poisoned baits from
lire stock and it is not advisable to have the baits close to barnyards
where fowls are kept, as they may be poisoned by eating the dead flies.=


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Transcriber Note

Minor typos have been corrected. Illustrations were moved to prevent
splitting paragraphs. Produced from files generously made available by
USDA through The Internet Archive. All resultant materials are placed in
the Public Domain.