Insects have developed several strategies for living in the diverse flows of lotic systems. Some avoid high current areas, inhabiting the substratum or the sheltered side of rocks. Others have flat bodies to reduce the drag forces they experience from living in running water. Some insects, like the giant water bug (Belostomatidae), avoid flood events by leaving the stream when they sense rainfall. In addition to these behaviors and body shapes, insects have different life history adaptations to cope with the naturally-occurring physical harshness of stream environments. Some insects time their life events based on when floods and droughts occur. For example, some mayflies synchronize when they emerge as flying adults with when snowmelt flooding usually occurs in Colorado streams. Other insects do not have a flying stage and spend their entire life cycle in the river.