Biological studies on Tabanustaeniola P. de B. adults [Diptera: Tabanidae]

An account is given of studies in Egypt on the adults of Tabanus taeniola P. de B. [cf. next abstract], which is the most abundant Tabanid there and is a serious pest of cattle, horses and camels. The studies were carried out mainly in the laboratory, where the adults were provided with citrated blood, water and sugar or a sucrose solution. Adult emergence generally occurred between 10.30 a.m. and 2 p.m. Pupae about to give rise to adults were able to work their way to the surface through a column of dry sand up to 2 m high, but were unable to penetrate more than 10 cm of wet sand. A temperature of 27 deg C was optimum for adult emergence. At 27 and 32 deg C, the interval between emergence and the first flight averaged about 3.1 and 2.6 h for females, respectively, and about 2.9 and 2.5 h for males. The corresponding intervals between emergence and the first feed averaged 6 and 5 days, respectively, for females provided with blood, 4.5 and 3.7 h for females provided with a 10% sucrose solution, and 4.4 and 3.6 h for males provided with the sucrose solution. It was found that the females were unable to take a blood-meal unless they had first fed on a sugar solution. In the laboratory, females provided with sucrose lived for averages of 32.3 days in June-July and 46.6 days in October-November; the corresponding figures for males were 27.6 and 38.3 days. In the insectary, the preoviposition period averaged about 9.6 days in June and about 15.3 days in November. In the field, the females oviposited on aquatic plants at the edges of irrigation canals.