A network of experiments was established in three different agroecological areas at the periphery of the Central Plain of Thailand during three successive years to assess the effect of a multiple insect pest complex on cotton yield loss. A large range of combinations of jassid and bollworm injuries was achieved from the application of several insecticide treatments and sowing dates. Other pests were of minor incidence. Seed-cotton yield varied from 0 to 3600 kg/ha, and yield losses due to pests ranged between 0 and 100% of the attainable yield. Damage mechanisms were addressed through path coefficient analysis of the interaction between injuries and plant compensation. Before boll production, jassids were the most serious pests, while bollworms had a positive effect on vegetative growth. At the fructification stage, bollworms were very harmful, while sucking insects such as jassids became progressively less important. Injuries did not necessarily lead to yield losses because of the plant compensation ability. Cotton response to pest injuries depended on the development stage and crop status. Decisions made on cotton protection against pests should thus consider the development stage of the crop and interactions between injuries instead of the traditional single pest population threshold. This study of a plant–pest system exemplifies the need to incorporate plant compensation processes in the design of pest management programmes aiming at reducing insecticide use.