BIOLOGY AND CONTROL OF TABANIDS, STABLE FLIES AND HORN FLIES

Tabanids are among the most free living adult flies which play a role as livestock pests. A single blood meal is used as a source of energy for egg production (100-1,000 eggs per meal), and females of certain s pecies can oviposit before a blood meal is obtained (autogeny). Theref ore the maintenance of annual populations requires successful oviposit ion by only 2% of females. Wild animal blood sources are usually avail able to maintain annual tabanid populations. Larval habitats are also independent of domestic livestock. Thus, the rise of repellents or par tial repellents is the only effective chemical strategy to reduce the incidence of tabanids tabanids on livestock. Permanent traps (and poss ibly treated silhouette traps) can be employed to intercept flies Sele ctive grazing or confinement can also reduce the impact of tabanids. S table fly adults ale dependent on vertebrate blood for survival and re production, but the amount of time spent in contact with the host is r elatively small. Stable fly larvae develop in manure, spilled feed and decaying vegetation. Management of larval habitats by sanitation is t he key to stablefly control. Treatment of animals with residual insect icides can aid in control; thorough application to the lower body part s of livestock is important. Proper use of modified traps using either treated targets or solar-powered electrocution grids, can be effectiv e in reducing stable fly populations. Adult horn flies spend the major part of their time on the host, and the larvae are confined to bovid manure. Therefore, almost any form of topical insecticide application for livestock is effective against horn flies, in the absence of insec ticide resistance. Treatments should be applied when economic benefit is possible; economic gains are associated with increased weaning weig hts and weight gains of yearling and growing cattle. Oral chemical tre atments (insect growth regulators or insecticides) administered at app ropriate rates via bolus, water, food ol mineral mixtures can inhibit horn fly larval development. However, adult horn fly movement among ca ttle herds limits the use of larval control for horn fly population ma nagement The augmentation of native parasites, predators and competito rs has been attempted and even promoted for horn fly and stable fly co ntrol, but evidence for the success of such programmes is equivocal.