Laboratory Insecticide Screening, L. Canus, Yakima, Washington, 1972

L. canus larvae were collected in the fall of 1971 from Grandview, Washington, and helJat 40°F until the tests were conducted. The soil used was “river-bottom soil”, sandy loam, <0.5% organic matter, sifted with 8-mesh sieve. The bioassays were conducted as follows: insecticides were mixed with air-dry soil in a Twin shell dry blender for 15 min, after which later was added to the soil (2.7% moisture), and the treated soil was placed in 0.5-pt Mason fruit jars. The dosage rates simulated broadcast treatments, and the incorporation of materials to 6 inch in depth. Two boiled wheat grains were pushed down ca. 1 inch into the soil of each jar. One wireworm was placed in each jar; if the wireworm did not burrow into the soil within 1 min, the wireworm was replaced. Regular jar lids were used, but they were not secured tightly. Each treatment consisted of 10 jars. The jars were held in a laboratory maintained at ca. 20 to 25°C. The jars were checked once weekly to determine mortality, which included any dead or moribund larvae. At the weekly checks, moisture was added to the soil as required, two new boiled wheat grains were added, and the same live larvae were replaced in the corresponding jars. Four separate tests were conducted, and the results are summarized in the table.