This book consists of the basic information associated with the entomological research including cotton insect pests control. It also has the host plant tolerance concept for defining the future eco-friendly control measures of insect pests. Results showed that maximum population of cotton mealybug 48/plant was found on AKSUN, that was statistically similar with ITSIT and LONAK having population of mealybug 41 and 34.3 per plant respectively at 35 days post release. Minimum population of cotton mealybug growth occurred on cholai 14.22 whereas intermediate population of cotton mealybug on hazardani 22.33 mealybugs/plant. Tolerance level indicates that aksun plant had lower level of tolerance toward mealy bug than all the tested plant species. Tolerance limit amongst the tested plant species ranged from 0.33 to 1.66. Maximum limit was found on hazardani, followed by itsit and lonak, but minimum on aksun and cholai. It is clear from the results that hazardani exhibited tolerance toward mealy bug infestation.