March 1956 ARS-33-18 
United States Department of Agriculture 
Agricultural Research Service 
A SAMPLING FORK FOR ESTIMATING POPULATIONS 
OF SMALL ARTHROPODS 
1/ 
By Charles F. Henderson, Entomology Research Branch— 
When studies of the biology, ecology, and control of the brown wheat 
mite (Petrobia latens (Mull.)) were planned, it was first necessary to 
develop a method of estimating mite populations on various small 
grains. The first method tried was to dislodge the mites by brushing 
the host plant back and forth with the hand, and to count those that fell 
on a white card held beneath the foliage. These mites readily fall to 
the ground when the plant upon which they are feeding is disturbed. 
However, this procedure was too slow where large numbers of small- 
unit samples had to be taken quickly under comparable conditions of 
temperature, light, and time of day. Population estimates in plots 
Sampled early in the day were not comparable with those taken later. 
Furthermore, a method was desired in which the samples could be 
taken to the laboratory and the mites counted under more favorable 
conditions. The apparatus and technique developed for these studies 
are described herein. 
Description of Fork 
In the fall or winter when the plants are small, the most satisfactory 
population estimates may be made by counting the mites on the foliage 
of 1-foot sections of planted row, with a head binocular (fig. 1). In the 
spring and summer after the plants had begun their upright growth, 
the mites were caused to drop from foliage to adhesive-covered glass 
slides held in a galvanized-iron sampling fork (fig. 2), similar to one 
described by Lawson (1). This fork consists of four tines attached to 
a tubular steel handle that extends from the base at an angle of about 
15 degrees. Around the edge of each tine is a retaining rim. The 
points of the tines are beveled on the bottom to prevent them from 
digging into the ground when the fork is pushed along the soil surface. 
The slides are of single-strength window glass, and just large enough 
to slip into the rectangular chamber of the tine. 
ay} In cooperation with the Kansas and Oklahoma Agricultural Experi- 
ment Stations. Contribution No. 655, Department of Entomology, Kansas 
Agricultural Experiment Station. 
