To obtain an expellent for wasps excellent in rapid effect, and to provide an effective exterminating method capable of instantaneously making flying behavior of aggressive wasps quiet and stopping the behavior and further killing alive wasps.

The expellent for wasps comprises at least one kind of a volatile liquid ingredient selected from the group consisting of iso-pentane, n-pentane and cyclopentane. The method for exterminating wasps is characterized by applying the expellent to a nest of wasps and transpiring the volatile liquid ingredient in the nest and stopping behavior of wasps in the nest.