The Distribution and Sampling of Insect Populations in the Field With Special Reference to the American Bollworm, Heliothis Obaoleta Fabr.

SUMMARY The problem associated with estimation of insect activity is discussed. A precision experiment, undertaken to investigate the nature of the egg‐laying of the American bollworm, is described. The nature of the distribution is investigated. Correlation trials between the two counts show that the same portions of the crop retain their relative attraction to the bollworm moth over short periods. The effect of subdivision of the area on the sampling error is analysed. Both egg as well as plant number figures per 3‐yard length show a greater variation between than within rows. Correlation and regression coefficients prove a very close relationship between plant number and eggs laid. Eliminating the effect of plant number eliminates this greater variation for the first egg‐count figures. In the second count the variation between rows is still significantly greater. The reason for this is discussed. Considerations affecting the sampling technique developed from the precision data are discussed. The sampling method is explained and two examples are given. From the analysis of these the system is shown to sample adequately the fields and fulfills the requirements of the survey.