Temporal Patterns of Emergence and Reproductive Behavior of the Hessian Fly (Diptera: Cecidomyiidae)

Under controlled laboratory conditions, the diel emergence pattern of male Hessian flies was bimodal; the majority of males emerged from 1500 to 1800 hours (CST) and a secondary peak of emergence occurred from 0600 to 0800 hours. In the absence of females, the onset of male activity (walking or flying) was a function of time of day rather than of male age; afternoon-emerged and morning-emerged males became active about 10 and 16 h after emergence, respectively, or 5–6 h after the onset of the scotophase. Males continued to exhibit walking and flight behaviors until death at about 17 and 21 h after emergence for afternoon- and morning-emerged males, respectively. In the presence of calling females, morning-emerged males sat for 45 min before taking flight and copulated about 10 min later. Female emergence was unimodal; 99.5% of total emergence occurred from 0100 to 0900 hours with a peak at about 0500 hours. Females began calling about 8.8 min after emerging and continued to call until 1000–1100 hours. There was a strong inverse relationship between the time of emergence and the duration of calling. On the second and third days after eclosion, females exhibited calling behavior from the early hours of the morning until 1000–1100 hours. By the morning of the fourth day after eclosion, 90% of all females were near death or had died. For both sexes, wing length was a strong correlate of fresh weight. Reproductive potential of both sexes, as measured by the number of females inseminated per male and the number of oocytes per female, was strongly correlated with body weight and wing length.