E-498 March 1940
A CATTLE FLY TRAP FOR THE CONTROL OF HORN FLIES
By Wo G. Bruce,
Division of Insects Affecting Man and Animals
The horn fly (Haematobia irritans (L.)) iS one of the important
insect pests attacking cattle in the United States-. In areas of horn
fly abundance the cattle industry suffers severely, as evidenced by the
loss of flesh and the reduction of the milk supply. Furthermore, these
biting flies often produce sores that become infested with screwworms
(Cochliomyia americana C. and P.).
There are several methods of reducing the numbers of horn flies.
These are: (1) Scattering the cattle droppings so that they will dry rapidly
and the larvae will thereby be killed, (2) applying fly sprays, (3) treating
cattle manure with chemicals. (4) giving the cattle an internal medication
which will render the droppings toxic to horn fly larvae,l_/ (5) using splash
boards on vats in which cattle are dipped, and (6) operating traps that
capture the flies on the cattle. The effectiveness of these varies in scope
An effective, inexpensive, and practical method of horn fly control
is the operation of the cattle fly trap2/ developed by the Bureau of Ento-
mology and Plant Quarantine. This trap has proved effective, both on the
range and at dairies, not only in controlling the horn fly but also in
greatly reducing the population of another serious pest. the stable fly
(Stomoxys calcitrans (L,)).
i/Bruce, W. G. The use of phenothiazine in the medication of cattle for
the control of horn flies. Jour. Econ. Ent, 32 (5): 704-706. 1939.
2_/Bruce, W. G. A practical trap for the control of horn flies on cattle.
Jour. Kans. Ent. Soc. 11 (3): 88-93, illus. 1938.
Description of Trap
The trap is of simple construction and can be built at a relatively
small cost by any person handy with tools (see attached drawings and specifi-
cations). The framework of the trap is 7 feet wide, 6 feet high, and 10
feet long. The base of the frame is made of 2- by 8-inch lumber and the
remainder of 2- by 4-inch lumber. All pieces are securely bolted together
with 3/8-inch bolts. The top is made of any inexpensive lumber or other
opaque material. The passageway through the trap is 33 inches wide and
approximately 6 feet high, and is lined along the sides with heavy, large-
mesh, wire fencing. This heavy wire fencing extends around the ends of the
frame, and three strands of barbed wire connect the outermost uprights so as
to protect the trapping elements from being damaged by the cattle. On each
side of the passageway, set behind the fencing, are three screen trapping
elements, each 37-1/2 inches wide, 9 inches deep, and 5 feet high. These
screen trapping elements are made of 18-mesh screen and are of a modified
tent-trap construction, i. e., the screen on the side of the element facing
the passageway is folded in a series of Z's. (Note in drawings (fig. 2, F)
that the almost horizontal parts of the Z's are slightly inclined to forestall
the accumulation of dead flies thereon.) The holes through which the flies
enter the trapping element are three-sixteenths by three-eighths of an inch
in size and are placed three-fourths of an inch apart along the inner acute
angles of the Z's. These holes are easily and quickly made by the use of a
three-eighths-inch cold chisel with the cutting edge notched like a V
(fig. 3). Each trapping element may be provided with a door for use in re-
moving the dead flies, or the whole back may be removed for that purpose.
Two sets of curtains and six or eight weighted strips are used to
dislodge the flies as the cattle pass through the trap. Each set of curtains
consists of three pieces of heavy, dark-colored canvas -- two pieces 20 inches
by 6 feet and one short piece 24 by 30 inches. The two long pieces of one
set are attached to the frame at the top and part way down the sides of the
passageway between the first and second pairs of trapping elements. These
long curtains, being fully half as wide as the passageway, meet at the cen-
ter. The short curtain is suspended from the top on the opposite side of
the cross piece to which the long curtains are attached. This short curtain
serves to brush the flies from the backs of the cattle and also to darken the
space above the animal, which is opened by the parting of the long cur-
tains. The other set of curtains is installed in -the same manner between
the second and third pairs of trapping elements. The weighted strips are
made of three thicknesses of heavy canvas 4 inches wide and 6 feet long and
are suspended from the X-shaped cross pieces at the top between the two sets
of curtains. The weights may be small pieces of lead, iron, or other heavy
material weighing about 4 ounces and riveted to the lower end of the strip.
These weighted strips flap about the body and legs of the animal as it
passes through the trap and dislodge flies not reached by the curtains.
Location of Trap
The trap must be located in a place where the cattle will be com-
pelled to use it frequently. An ideal location is in a lane where the cattle
must pass through the trap on their way to and from water or to a dairy barn,
Or a fence can be constructed around the water supply and the trap placed in
the gateway. Such locations insure daily use of the trap and, obviously, the
more often the cattle go through the trap the more pronounced will be the
control of horn flies.
The trap should be set up several weeks before the fly season so that
the cattle will become thoroughly familiar with it and the trap be in fulJ
operation before the flies become annoying. The process of familiarizing
cattle with the trap is slow but important. After the trap has been set up
the cattle should be permitted to pass through it for a week or more before
any of the curtains or strips are installed. Then the curtains and strips
are added, piece by piece, at 2- or 3-day intervals until all are in place.
No difficulty has been experienced in familiarizing cattle with the trap,
even with wild range cattle. Once they get used to the trap thn cattle will
use it of their own accord when flies become annoying.
Care of Trap
After the trap is in operation it needs little attention. There is
nothing to get out of order. However, it is advisable to make weekly in-
spections and, at time of inspection, to remove dead flies and destroy
spider webs. Occasionally hair from shedding cattle will collect on the
screen Zs, particularly along the lower two or three rows. This, and
any other foreign material, should be removed so the holes through which
the flies enter will not become clogged.
Bill of Materials for Building the Trap
2" x 4" x 10'
2" x 4" x 51"
2" x 8" x 10'
2" x 4" x 7'
2" x 4" x 3'
2" x 4" x 6'
i" x 9" x 45"
3/4" x 8" x 5'
3/4" x 8" x 3'
3/4" x 4" x 3'
3/4" x 2" x 3'
3/4" x 1-1/2" x 5'
3/4" x 1-1/2" x 37-1/2"
3/4" x 3/4" x 5"
3/4" x 3/4" x 7-1/2"
3/4" x 3/4" x 5"
1 and 2
A, B, C, D, I-a
A, B, C, D-b
A, B, C, I-c
A, B, C, D, I-e & f
A, B, C, D-t
B, F, H-1
D, E, F, H-k
A, F, G-d
D, G, H-m
X-shaped cross members.
Frame, long cross pieces.
Frame, short cross pieces.
Trapping elements, sides.
Trapping elements, bottoms
Trapping elements, front b
Trapping elements, tops.
Trapping elements, backs.
Trapping elements, backs.
Trapping elements, Z's.
Trapping elements, Z's.
Trapping elements, stops.
Trapping elements, all sci
screen wire, galv., 18-mesh,
37" wide, 100 ft. long
carriage bolts with nuts and
washers, 3/8" x 3-1/2"
carriage bolts with nuts
and washers, 3/8" x 5-1/2"
nails, 8d common
nails, 8d boxing
screws, 1-3/4", No. 8, )
F. H. B.
sheet iron, galv., 26 ga., )
6" x 6")
turn kncbs, small )
fencing, stock, heavy,
canvas, heavy, 20" x 30"
canvas, heavy, 20" x 6'
canvas, heavy, 4" x 6'
hook and eye screws
D-z, G, H
A, B, C-r
Backs, tops, and Z's of trapping elements.
For holting long cross Fieces to uprights.
For bolting uprights to frame.
For tacking screen on trapping elements.
(Small doors for trapping elements.
(If no doors are used, make backs of
(trapping elements entirely of screen
(wire and fasten back to rest of elements
(with eight screws.
Sides of passageway to protect trapping
elEnEnts from animals.
Fastening stock fencing to sides of pas-
Short curtains on short cross pieces.
Long curtains on opposite side of short
Long strirs, on X-shaped cross member.
For holding trapping elements in place.
- - ---- ---- -----
Explanation of Figures
Fig. 1, A. Side view of trap.
Fig. 1, B. End view of trap. --
Fig. 1, C. Longitudinal section of trap (narrow canvas strips not shown).
Fig. 1, D. Cross section of trap.
Fig. 2, E. Front view of trapping element.
Fig. 2, F. Interior view of one end of trapping element showing construc-
tion of Z's for attachment of screen wire.
Fig. 2, G. Back view of trapping element.
Fig. 2, H. Top view of trapping element.
Fig. 2, I. Top view of trap (roof removed) showing construction of X mem-
bers and attachments of curtains and strips.
Fig. 3. Cold chisel for cutting holes in trap.
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UNIVERSITY OF FLORIDA
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