Urine delivery of cyromazine for suppressing house and stable flies (Diptera: Muscidae) in outdoor dairy calf hutches

In a series of 4 trials, dairy calves housed in outdoor hutches were administered technical cyromazine daily at rates of 0, 0.1, 0.5, and 1.0 mg/kg body weight. Cyromazine was excreted primarily in the urine. The 2 highest rates prevented the development of immature stages of both the house fly, Musca domestica L., and the stable fly Stomoxys calcitrans (L.). Analysis of calf body tissues for cyromazine and its metabolite, melamine, indicated that highest combined residues (less than or equal to 0.35 ppm) were found in the kidney. Lower levels of residues were found in kidney fat and liver, and occasionally in round muscle.