July 1942 ET-197
United States Department of Agriculture
Bureau of Entomology and Plant Quarantine
A RECOVERY CAGE TO DETERMINE THE NUMBERS OF FLEA BEETLES EMERGING
FROM SOIL SURROUNDING HOST PLANTS
By J. U. Gilmore and Clemence Levin,
Division of Truck Crop and Garden Insect Investigations
The apparatus described herein was developed at the Oxford,
N, C., laboratory and has been used rather extensively during
the last several seasons for obtaining estimates of the numbers of
adult tobacco flea beetles (E!trix parvula (F.)) emerging from the N
soil, particularly in tobacco plant beds. With slight modifica-
tions in shape, size, and covering it can be used in experiments
with many different insect pests where an efficient cage suitable
for retaining such insects is required.
The finished cage is cylindrical and will cover a space
equal to 1 square foot on the soil surface. The frame is con-
structed of -inch rods of black malleable iron and measures 21
inches in height and 13 inches in diameter (fig. 1, A). The two
circles are made from single lengths of the rods, 42.4 inches long,
which are shaped in a pipe former and the ends welded together.
The three supporting rods are spaced at equal distances about the
circles, The upper circle is welded to the ends of the three up-
right rods, which are then attached to the outer side of the lower
circle. After the eight welds are made the frame is painted to
retard oxidation of the metal.
Cloth, consisting of 32 by 28 strands per inch, is sewed to
form a cylinder 36 inches long, which is slipped over the frame.
This cloth envelope is sewed to the lower circle and attached with
thread at six places on the upper circle. To preserve the cloth
near the ground, a strip 3 inches wide around the base of the cage
is sprayed with paint.
The cage is placed in position for operation by forcing the
projecting rods into the ground and banking 1 or 2 inches of soil
around the base to make it insect-tight. The open cloth top is
closed with a string slip knot, and the other end of the string is
attached to a stake, as shown jn figure 1, B.
While these cages are not often required to withstand rough
usage, they are substantial enough to be operated for many seasons.
Some of them have been used during four seasons to date and, with
annual painting, can be used indefinitely (fig. 2). The cloth
envelopes, the bases of which by necessity must come in contact
with the soil, last from a month to 6 weeks, even under conditions
of excessively heavy precipitation. This is sufficient time for
the development and emergence of a single brood of the tobacco flea
beetle. During a 30-day period a total of 796 beetles were retained
and recovered in one of these cages situated in a tobacco plant bed.
Actual recovery is effected by opening the top of the cloth cylinder
and removing the beetles in any manner desired.
Figure 2.-A series of recovery cages in operation in a tobacco
plant bed adjacent to a tobacco field.
Figure l.-Recovery cage. A, Recovery cage frame, uncovered.
B, This recovery caga, covered, staked, and mounded, is
ready for operation.
UNITED STATES DEPARTMENT OF AGRICULTURE
OFFICE OF THE SECRETARY
WASHINGTON, D. C.
PENALTY FOR PRIVATE USE TO AVOID
PAYMENT OF POSTAGE, $300
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