252 



The Efficacy of Methoprene as a Feed Additive 

 When fed to hens at 10 ppm, methoprene produced fly mortalities of 

 85.00% in the laboratory and 55.10% in the field. When fed at 1 ppm, 

 methoprene produced a laboratory mortality of 17-50%. Morgan et al. 

 (1975) produced 70.9% fly mortality with 5 ppm methoprene diets, but a 

 mortality of 99-3% required 100 ppm methoprene diets. Low mortalities 

 produced under field conditions were attributed to the rapid decom- 

 position of methoprene (Schaefer and Dupras, 1973). This rapid de- 

 composition eliminates methoprene for use as an oral larvicide. Larval 

 moits are not affected by low concentrations of methoprene and the 

 critical pupal molt occurs after the larvae have left the area of 

 methoprene concentration. 



Consumption of methoprene caused no significant differences in feed 

 consumption or egg production except in one case where hens were allowed 

 to run out of feed. Morgan et al. (1975) found no differences in hen 

 weights due to methoprene diets. 



Methoprene as a Topical Larvicide 



2 

 Methoprene applied topically to manure at 1076 mg/m produced mor- 

 talities of 90.0 and 99-0% in laboratory-strain flies 3 days pcst- 



2 

 treatment. Applied at 538 mg/m , 3~day post-treatment mortalities of 



73.0 and 96.0% were produced, but this result may not be indicative of 

 what is occurring in the field. 



With a residual of 3 days or longer, methoprene applied topically 

 would be ideal for spot treatment of house flies in pouliry manure. 

 The granules are in a form that is convenient to use and could be dis- 

 pensed from the -ear of a rototiller. Tilling would increase the 

 chances of larvae coming into contact with methoprene. 



