AGE STRUCTURE AND REPRODUCTIVE COMPOSITION OF SUMMER MUSCA-AUTUMNALIS(DIPTERA, MUSCIDAE) POPULATIONS ESTIMATED BY PTERIN CONCENTRATIONS

Pterins in face flies, Musca autumnalis DeGeer, were measured spectrof luorimetrically to estimate the chronological ages of adults in natura l summer populations. The age distributions showed a systematic unders ampling of young young males. Experimental, Gompertz, and Weibull mode ls were fitted to the age distributions. A 1-parameter exponential mod el suggested mean daily survival rates of 0.83 for female face flies, and a mean life expectation of 5.5 d. But the Weibull model best fit t he age distributions, providing mean life expectations of 10.1 and 11 d for males and females, respectively. Ovarian dynamics were examined with respect to chronological age and delays were detected in vitellog enesis and oviposition. Face fly populations seemed to reproduce at le ss than the maximum rate allowed by prevailing temperatures, at which it was estimated that an average female would undergo 2.2 ovarian cycl es and have a lifetime fecundity of 28.5 female progeny.