September 1942 ET-201 
 
 United States Department of Agriculture 
 
 Agricultural Research Acministration 
 Bureau of Entomology and Plant Quarantine 
 
 METHOD AND EQUIPMENT FOR CONDUCTING L/.BORATORY 
 
 EXPERIMENTS WITH INSECTICIDES FOR THE CONTROL 
 
 OF INSECTS THAT PUPATE IN THE SOIL 
 
 By Oliver I. Snapp, 
 
 Division of Fruit Insect Investigations 
 
 Laboratory experiments with soil fumigants against plum 
 curculio larvae and pupae in the soil are carried on at Fort Valley, 
 Ga., in boxes (fig. 1) made of 1-inch rough boards, with inside 
 measurements of 1 square yard and 6 inches deep, and equipped with 
 16-mesh wire cloth lids on hinges; all cracks are puttied and the 
 tops are lined with felt strips to prevent the escape of adult 
 insects. Such boxes would no doubt be satisfactory for similar 
 experiments with other insects. Plum curculio pupation usually 
 takes place within the top 3 inches of soil, and therefore a box 
 6 inches deep is adequate for experiments with that insect; however, 
 a deeper box would have to be used for insects that pupate under 
 field conditions at a depth in excess of 6 inches. 
 
 The boxes are filled with soil, after which 30 bottomless 
 1" X 4" glass tubes are inserted in the soil, to a depth of about 
 Zj inches, across the center of each box (fig. 2) for, the purpose 
 of determining the stage of development of the insects within each 
 box and to determine the rapidity with which the material under 
 test kills individual larvae or pupae. As each box holds 1 square 
 yard of soil, the material to be tested is applied at a rate of 
 a unit per square yard. 
 
 Two full-sized larvae are placed in each bottomless tube, 
 and 750 full-sized larvae are placed en the soil in each box, to 
 make their way into the soil in a normal manner in preparation for 
 pupation. The tubes projecting about one-half inch above and 
 3 inches into the soil prevent the escape of the individuals from 
 within the tubes and the entrance into the tubes of the larvae 
 placed on the soil outside them. Individual tubes are removed 
 periodically to observe the development of the insects within each 
 box, so that treatments can be made after the larvae construct soil 
 cells in cases where the materials are being tested against larvae 
 in soil cells, after all individuals enter the pupal stage in cases 
 
2 - 
 
 where the materials are being tested against pupae, or after 
 transformation to adults takes place in cases where the tests are 
 against adults before they leave the soil. 
 
 After the box has been treated, the remaining individual 
 tubes are removed at intervals to determine the rapidity of kill 
 from the material under test and for individual mortality records. 
 After the adults begin to emerge, each box is examined daily and 
 the adults are removed and recorded to determine the percentage of 
 mortality of the 750 individuals placed in the box outside of the 
 vials. 
 
Figure 1.— Boxes for experiments with insecticides against 
 larvae and pupae in the soil. 
 
 UBRARY 
 STATC PLAOT board 
 
Digitized by the Internet Archive 
 in 2013 
 
 http://archive.org/details/methodequipmentfOOunit 
 
Figure 2. — Box equipped with 30 bottomless glass 
 tubes for individual specimens. 
 
NIVERSITY OF FLORID'^,,, 
 
 3 1262 09240 8938