Permethrin for Biting-Fly (Diptera: Muscidae; Tabanidae) Control on Horses in Central Luzon, Philippines1

Abstract

Rub-on treatments of 0.5, 1.0, and 1.5% permethrin emulsions provided 7–10-day control of Stomoxys calcitrans on ca. 100 horses maintained at the Clark Air Base stables in the Philippines. Emulsions of 1.0% permethrin rubbed on or sprayed on ½ of the herd also gave 7–10-day control during the late rainy season and throughout the dry season on central Luzon. Longer control was obtained during the driest periods. Alsynite® panels treated with 3.2 g active ingredient (AI)/cm2 of permethrin wettable powder reduced the number of stable flies/horse by ca. 50% over a 1-wk period during the dry season. Permethrin-impregnated net blankets (0.28 mg AI/cm2) reduced stable-fly populations ca. 60% on 30 separately pastured horses wearing the net blankets. Net blankets treated with 0.56 mg AI/cm2 retained their insecticidal effectiveness for more than 7 weeks under early rainy season field conditions. Physical damage to the net blankets and difficulties in coordinating net blanket use were the primary factors limiting their usefulness for biting-fly control. Tabanus megalops (Diptera: Tabanidae) and other horse flies were controlled for 3–6 days following rub-on or spray-on treatments of 1.0% permethrin to ½ of the horses in the experimental group.