House fly (Diptera: Muscidae) monitoring method comparisons and seasonal trends in environmentally controlled high-rise, caged-layer poultry houses

Baited jug traps and 0.093-m2 counting stations were used to monitor adult flies within the manure pits of five central Pennsylvania high-rise, caged-layer poultry houses. House flies, Musca domestica L., were the principal fly species at four of the houses and black garbage flies, Ophyra aenescens (Wiedemann), at the fifth house. Correlation analyses were used to compare counting-station (three positions: pit upper walls, lower walls, and posts) and baited jug trap house fly counts. Station-count positions were fairly well correlated with each other (r2 = 0.20-0.84). Poor correlations between jug traps and most counting stations (r2 = 0.07-0.57) suggest that 0.093-m2 counting stations were not reliable reflections of population density changes. Seasonal influences in the relationship between house fly activity indicated by counting stations, house fly abundance obtained by baited jug traps, and temperature were examined by linear regression. Temperature accounted for 19-26% of the variation at two of the houses but only 0-7% at the other two houses. The distribution of ventilation fans in the pit walls significantly affected baited jug trap counts