Spatial pattern of distribution of populations of three insect species, namely, Amrasca biguttula biguttula (Ishida), Bemisia tabaci (Genn.) and Aphis gossypii Glov. was studied in Upland cotton (Gossypium hirsutum L.) at an interval of 13–15 days during July, August and September in Punjab. The populations were found to be aggregated from the beginning of season upto 25 August in jassid nymphs, 12 August in whitefly adults and the end of season in apterous aphids. Environmental heterogeneity at low population in July and innate behaviour at high population were responsible for the aggregated dispersion in each of the three homopterans. Based on these observations the appropriate number of samples required to be drawn for population studies were determined which varied with change in pest density in each case.

Studies on critical time of insecticidal protection in relation to damage by aphid, Aphis gossipii Glover and leafhopper, Amrasca biguttula biguttula Ishida on plant growth and yield of okra revealed that 21–42 days after germination, was the most critical time prior to fruiting. Application of carbofuran at the time of sowing was redundant. Effective plant protection 21–42 days after germination resulted in lowest leafhopper and aphid infestation and subsequently the highest benefit to cost ratio.

Studies on seasonal patterns of okra leafhopper, Amrasca biguttula biguttula Ishida were conducted for two years. Time series analyses were adopted for working out weekly seasonal index of okra leafhopper. Low incidence of leafhopper was recorded from June to mid-January. Results further revealed that incidence of leafhopper was highly correlated with minimum temperature. There was no discernible time lag for population increase of leafhoppers. Prediction of leafhoppers at different crop growth stages for various months of sowing was done using dummy variable technique.