Some Factors Affecting Flight Activity in Individual Milkweed Bugs (Oncopeltus)

Abstract

1. Individual adults of Oncopeltus were tested repeatedly at 2- or 3-day intervals, using tethered flight, to determine the amount of flight activity as measured by flight duration. 2. The peak period of activity occurred 8 days after the final moult with later flights scattered and showing no concentration at a particular age. Deposition of cuticular growth rings ceased at about 7 days; the peak activity was thus post-teneral and probably represents migration. 3. Only 23.8% of bugs tested showed flights of over 30 min. Those bugs which flew for long periods at 8 days were more likely to show long flights at a later age than were bugs which did not fly at day 8. There thus seems to be a behavioural polymorphism with distinct ‘flyers’ and ‘non-flyers’. 4. More females, 30.7%, than males, 18.1%, exhibited flights of over 30 minutes. Males which did have such long flights were, however, more likely than females to have them repeatedly. 5. In both sexes virgins seemed to be more active in respect of long flights than bugs allowed continuous contact with the opposite sex. 6. Calculations based on estimates of flight speed and total duration of flight indicate that an individual migrant Oncopeltus is capable of covering a considerable distance, 100 kilometres or more, during its lifetime.