I believe that high summer temperatures can affect insects by accelerating their metabolism. In cases of very high (extreme) temperatures it can influence behavior, causing insects to seek shelter in the hottest hours of the day. But not killing. Even very low temperatures can be more harmful, adversely affect the metabolism, prolong the development time and even cause death.
It is speculated that climate change may lead to rise in pest population particularly insects. So increase in temperature due to climate change will boost the insect population.