Physiological age structure of adult tabanid populations (Diptera: Tabanidae) in Alberta, Canada

The physiological age was determined of female Tabanids collected by means of Manitoba traps [cf. RAE/B 54 p. 69] in June-August 1969 in south-western Alberta Atylotus incisuralis (Macq.). Hybomitra frontalis (Wlk.), H. itasca (Philip), H. liorhina (Philip), H. rhombica osburni (Hine) and H. rupestris (McDunn.) were regarded as autogenous as virtually no nulliparous flies were trapped. Maximum numbers occurred after mid-July, and only 1-15% of uniparous flies survived to the beginning of the third gonotrophic cycle. H. affinis (Kby.), H. arpardi (Szil.), H. lasiophthalma (Macq.), H. lurida (Fall.), H. nuda (McDunn.) and H. typhus (Whitney) were considered to be anautogenous as nulliparous females were frequently trapped. Maximum numbers occurred before mid-July; 19-51% of nulliparous flies survived to the beginning of the second gonotrophic cycle, and 31-63% of uniparous flies survived to the beginning of the third. It is considered that some completed the third cycle.