Climate change is possibly the most significant global change that has attracted the attention of scientific community all over the globe. Climate induced changes in pest activity are likely to affect agricultural production in several ways. Increased pest populations will stress crop plants and increase the risk of crop loss, reducing yield and/or quality of harvest. Moreover, as climate change progresses, the damages due to pests will compound and interact with plant stress due to the direct effects on crops because of changes in temperature, precipitation, and carbon dioxide levels. Insects are poikilothermic animals and therefore they are highly sensitive to their surrounding climate particularly the temperature. The possible effects of changing climate on insects could result in their outbreaks, migration, change in biodiversity, species extinction, change in host shift, and emergence of new pests or biotypes. Due to the climate change, there is an increase in number of insect pest population, out breaks of insects, increased number of generations and development of resistant biotypes. This would definitely increase the damage caused by the insect to decrease the crop yields, increase the cost on crop protection and thereby affect the economy. Possible effects of elevating temperatures, CO2, and precipitation on insects have been discussed in this chapter