VETERINARY ENTOMOLOGY Development of Granular Boric Acid Sugar Baits for House Flies (Diptera: Muscidae)

Freeze-dried, granular sugar baits containing boric acid as the toxicant were evaluated against house ßies,Musca domesticaL., in two bioassays with toxicant dose ranges of 3, 5, 7, 8, and 12%, and 3, 5, 9, 17, and 33% boric acid, respectively, calculated and expressed on a dry weight basis. Flies in bioassay 1 were mixed sex and unstarved and ßies in bioassay 2 were females only and starved 4 h before testing began. LC50s were 8.97 and 14.33%, and LT50s were 59.75 and 53.34 h in bioassays 1 and 2, respectively. Baits were tested at concentrations as high as 33%, however there was no indication of repellency as seen previously with liquid baits. Reasons for lack of repellency and potential uses for baits are discussed. Development of efÞcacious granular baits would allow the presentation of higher levels of boric acid in volumes much smaller than required for liquid baits.