Seasonal Distribution and Parasitism of Eggs of Tabanidae in Alabama1

Abstract

Tabanid egg masses deposited around ponds in the Auburn area of Alabama were enumerated and marked for future identification or were collected and held in the laboratory for emergence of tabanid larvae and parasites. Egg masses of Tabanidae were found from May 5 through mid-September 1966. The oviposition peak occurred June 2, 1966, when 358 masses were counted. A rapid reduction in numbers followed, and throughout July, August, and September only scattered egg masses were found. Egg masses that were collected and allowed to hatch in the laboratory were found to have a seasonal average of 14% parasitism. Percentage parasitism per egg mass ranged from 0 to 53%. The seasonal average number of eggs per mass was 189.6 for Chrysops sp. and 529.4 for Tabanus sp. The seasonal average hatch was 54.1%. Almost 32% of the eggs produced neither larvae nor parasites. Telenomus tabanivorus (Ashmead) was the only parasite collected from egg masses of Tabanus species such as T. atratus F. An undescribed species or Telenomus near tabanivorus was collected from egg masses of Chrysops sp.