Ectothermals escape very low temperature by hibernating. The body temperature of ectothermals fluctuates with the environmental temperature. That is why, they hibernate in winter and aetivate in summer to escape the harsh conditions.
Hibernation is the reduction of metabolic activities in an organism, which happens mainly during the winter months and is widespread in higher animals and also invertebrates including arthropods.
Examples: bats, prairie dogs and ground squirrels.