Changes of Behavior Pattern within the Fifth Nymphal Instar of the Milkweed Bug, Oncopeltus fasciatus (Dallas)

Abstract

The reactions of the fifth instar nymphs of the milkweed bug, Oncopeltus fasciatus to humidity, light and gravity were studied. The results showed that the reaction patterns changed during the instar and were affected by starvation. The normal nymphs were hygro-negative, photonegative and geonegative during the feeding period. These reaction patterns were less intense during the pre-feeding and post-feeding period. Starved nymphs shifted to hydropositive and geopositive, though their photoreaction remain unchanged. These reaction patterns were compared with the behavior of the insect in the field, and their adaptive value to the survival of the species was discussed.