Nictation is a dauer-specific hitchhiking behavior of Caenorhabditis elegans, which helps dauers to get on to other animals passing by. Nictation is only recently studied and little is known about the genetic and environmental factors related to this behavior. Here we show that several environmental factors including wind and temperature can affect nictation. We investigated how different isotypes respond to these environmental conditions. We are now screening QTL(s) that regulate variation in reaction norm of nictation behavior. We expect our study will help us to understand how gene-environment interactions regulate behavior.