Relationship of Microhabitat to Incidence of House Fly (Diptera: Muscidae) Immatures and Their Parasitoids at Dairy Farms in Central New York

Abstract

Weekly observations were made on the presence of house fly, Musca domestica L., and stable fly, Stomoxys calcitrans (L.), eggs, larvae, and pupae, during 21 wk at nine dairies in Cayuga County, New York. Laboratory-reared fly pupae were exposed at each site to monitor parasitoid activity. Incidence of fly immatures was significantly related to substrate, moisture, and location, but not to indoor or outdoor exposure. Incidence was greatest at wet sites, particularly in manure, bedding, and feed, and lowest at dry sites. Locations with the highest incidence were lean-to, silo, calf pen, outdoor manure pile, outdoor manure ramp, and manure lagoon. Incidence of Muscidifurax raptor Girault and Sanders, Urolepis rufipes (Ashmead), Spalangia cameroni Perkins (Hymenoptera: Pteromalidae) and total parasitism were positively associated with the presence of fly immatures, but Phygadeuon fumator Gravenhorst (Hymenoptera: Ichneumonidae) was independent. With respect to substrate, moisture, and exposure, parasitism was generally distributed in a pattern similar to that of the flies. However, incidence of parasitism was greater, relative to that of fly immatures, in grass and earth substrates, but lower in wet manure and feed. With respect to location, parasitism was high at manure ramps and low in calf pens and in manure sheds, relative to fly immatures. The guild of parasitoids attacking synanthropic muscoid pupae appears to cover all appropriate host microhabitats at dairies in central New York.