Infectivity of Serratia marcescens (Eubacteriales: Enterobacteriaceae) in Stomoxys calcitrans (Diptera: Muscidae)

Serratia marcescens Bizio, a facultative pathogen of insects, was isolated from stable flies, Stomoxys calcitrans (L.), collected from Nebraska beef cattle feedlots and dairies. Infection rates in laboratory-reared stable flies infected by topical exposures to the bacterium were 57 and 64% in two experiments. Per os exposures to sucrose and water solutions, and bovine blood inoculated with S. marcescens, produced mortality rates of about 45 and 10%, respectively.