Development of Sampling Designs for Egg and Larval Populations of the Wheat Midge, Sitodiplosis Mosellana (Géhin) (Diptera: Cecidomyiidae), in Wheat

The spatial and statistical distribution of eggs and larvae of the wheat midge, Sitodiplosis mosellana (Géhin), in wheat in northeastern Saskatchewan were investigated. The highest number of each stage occurred in the top third of the head and the lowest in the bottom third. Because of this the entire wheat head is considered an adequate sample unit for density estimates of the two life stages. Sample sizes required to estimate egg and larval populations with given levels of precision were determined. A sequential sampling plan for larval populations was derived using Green’s and Iwao’s methods. Both methods gave similar results; however, the number of samples required to reach a decision was higher using Green’s method than using Iwao’s.