MIGRATION IN THE GRASSHOPPER MELANOPLUS SANGUINIPES (FAB.). I. THE CAPACITY FOR FLIGHT IN NON-SWARMING POPULATIONS

A tethered flight assay which identifies migratory behavior in the grasshopper Melanoplus sanguinipes (Fab.) was developed. The validity of the assay was examined by flight testing individuals collected at random from migratory and from virtually non-migratory field populations. Behavior in the tethered assay was found to accurately reflect the relative amount of migratory behavior in the field populations. Migratory flight appears to occur in this species even in the absence of obvious swarming behavior. Interpopulation differences in flight behavior observed in the field insects were maintained in first generation laboratory-reared progeny. Results of this study imply that migration is likely to play a significant role in the ecology of M. sanguinipes, even in nonoutbreak populations, and is not likely to be a simple facultative response to unusual environmental conditions.