Refuge Size Preference in the Field Cricket Gryllus bimaculatus

Size preference for artificial refuges was examined in the adult field cricket Gryllus bimaculatus under laboratory conditions. Blinded crickets were placed individually in a container consisting of a circular arena and six different-sized artificial refuges (triangular tent-like shelters). The crickets were allowed to walk freely inside the container for a constant period. Size preference was evaluated by determining cumulative stay period in each shelter. When the depth of the shelters varied from 60 to 160 mm at 20-mm intervals, and the width was fixed at 30 mm, both males and females tended to remain in relatively longer shelters (≥ 140 mm). Females, in particular, exhibited a distinct preference for the longest shelter (160 mm). The width of the shelters was then varied from 20 to 40 mm at 4-mm intervals, and the depth was fixed at 100 mm. Although males did not show selectivity to specific shelters, females tended to select a shelter with a particular width (32 mm). These results suggest that adults of G. bimaculatus have size preferences for refuges under blinded conditions. However, the preferences may involve sexual differences as well.