United States Department of Agriculture
Bureau of Entomology and Plant Quarantine
A REVOLVING PLANT CAGE FOR USE IN INSECT SELECTIVITY STUDIES
By Jos. A. Gillett, University of Idaho Agricultural Experiment
Station, and J. R. Douglass, Division of Truck Crop and Garden
Insect Investigations i/
The revolving cage (fig. 1) herein described has been found
useful in conducting experiments with repellent spray materials
against the beet leafhopper (Eutettix tenellus (Baker)) and in de-
termining the comparative aversion of this insect to the various
varieties of sugar beets and beans. The construction and operation
is such that light and temperature factors are equalized and the
insects are allowed to select any of the plants contained in the
cage. A sliding partition separates the plants into compartments so
that the insects on each plant may be recorded.
The cage (fig. 2) is constructed on the wheel and one-half of
the axle of a discarded automobile. The axle was set in the con-
crete at a desired height above the greenhouse floor. The base of
the cage was constructed of 5-ply board 32 inches square. Four
holes, 4 inches in diameter (fig. 3), were cut on diagonal lines,
12 inches from the corner of the base, to hold potted plants. The
details of the cage construction are shown in figures 2, 3, and 4.
The rigidity of the cage will be improved if all joints are glued
and fastened with screws before the glue is dry. Steel corner
braces connecting the partition uprights with the cage frame are
also helpful. All wooden parts of the cage should be coated with
The corners of the cage were rounded to improve visibility
and to facilitate removal of the insects. The outer corner and a
portion of one side of each compartment were made of celluloid so
l/ The writers acknowledge the loan of a selectivity cage, from
Orin A. Hills, of the Bureau of Entomology and Plant Quarantine,
Grand Junction, Colo., laboratory, which aided in planning the cage.
They are indebted also to Beckford F. Coon, of the University of
Idaho Agricultural Experiment Station, and to E. H. Bean, of the
Bureau of Entomology and Plant Quarantine, for helpful suggestions
and assistance in building the cages.
that the insects could be easily observed. After the celluloid had
been tacked on the inside of the cage frame it was cemented to the
cage with acetone to insure an insect-proof enclosure. The top and a
portion of one side of each compartment were made of 30-mesh wire
screen to provide for circulation of air, and a grommet to hold a
cork was placed in the center of each screen so that the leafhoppers
could be easily removed.
The sliding partition was made from two pieces of 26-gauge
galvanized iron bent at right angles and welded in the form of a
cross to a 1/2-inch open pipe, as shown in figure 3. This pipe was
capped at the top and opened at the bottom and was used to introduce
the insects into the center of the cage. The l- by 2-inch uprights
in the frame were grooved and waxed so that the partition would
slide smoothly. The cage was made insect proof by the use of
cylindrical weather strips at all points where the sliding parti-
tion and the frame came into contact. The points of contact between
the sides of the cage and the partition with the base were made
tight with sponge-rubber weather strips.
Sash locks were used to hold the cage and base together dur-
ing operation. For removing the cage from the base to replace the
plants, a cord was run from the screw eyes placed at each corner
to a pulley anchored above. The cord was unhooked from the screw
eyes before the cage was set in operation.
The cage was rotated by means of a 1/4-horsepower electric
motor, an old cream separator being used for the reduction gear
(fig. 5). The separator-bowl housing was cut away to permit the
operation of a 5-inch pulley from the bowl spindle to a 2-inch
pulley on the motor by means of a V-belt. A 21-inch pulley placed
on the axle of the separator handle was connected to the automobile
wheel by 1/4-inch round belting. A belt guide aided in keeping the
belt in the proper position on the automobile wheel. Using the
pulley set-up as described, the cage rotated once in every 97
seconds. By using pulleys of different sizes it was easy to change
the speed of rotation. The separator and motor were mounted on a
wooden frame, which was fastened to a concrete block. To avoid
unnecessary vibration, sponge-rubber pads may be used under the
motor reduction-gear units. If desirable, an additional revolving
cage may be operated from the same motor and reduction-gear unit by
attaching another pulley on the opposite side of the axle of the
separator handle, as shown in figure 5.
The cage was raised by the pulley and cord from the base while
the potted plants were arranged in the holes cut in the base for
this purpose. The cage was then lowered and fastened to the
base by the sash locks, and the partition was raised, as is shown in
figure 6. While the cage was revolving the desired number of leaf-
hoppers were introduced through the 1/2-inch pipe into the center of
the cage. After the cage had been run for the desired length of
time, and while it was still rotating, the partition was lowered
quickly to prevent the insects from moving from one plant or com-
partment to another (fig. 7). The motor was then stopped, and the
insects from each compartment were removed by means of a long T-tube
sucker, and recorded.
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Figure l.-Perspective view of the cage.
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Figure 3.--Floor plan of the cage, showing metal partition in place.
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Figure 4.---Section showing construction of the cage top.
Figure 5.-Mounting of cage and motor.
Figure 6.--Cage with partition up.
Figure 7.--Cage with partition down.
UNIVERSITY OF FLORIDA
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