Field evaluation of three methods for monitoring populations of house flies (Musca domestica) (Diptera: Muscidae) and other filth flies in three types of poultry housing systems.

Analysis of field data collected over several years in three poultry housing systems (narrow caged-layer houses, high-rise caged-layer houses, and broiler-breeder layer houses) indicated that the baited jug-trap was a reliable method of sampling house flies, Musca domestica L.; sticky ribbons provided additional information on two other fly species. Relative frequency of house fly capture indicated that this fly was present in all poultry systems in North Carolina from May to October, while Fannia canicularls (L.) and Ophyra spp. were present in low numbers after July. Sticky ribbon indices were correlated with baited jug-trap indices for all three fly species in all poultry systems. Spot card indices were correlated with house fly abundance indices, but appeared to be influenced by other fly species in narrow and high-rise caged-layer houses. The relationship between the mean and variance of house fly abundance indices was used to determine the number of samples required to obtain estimates of house fly abundance with a fixed level of precision (CV = 0.10,0.15, and 0.20) in each poultry housing system. THREE SPECIES of filth flies are common in poultry production systems. These are the house fly, Musca domestica L., the little house fly, Fannia canicularis (L.), and "black garbage flies," Ophyra spp. (O. aenescens [Wiedemann] and O. leucostoma [Wiedemann], which are difficult to distinguish). Flies are often abundant and constitute a pest problem in poultry production systems, especially in chicken broiler-breeder layer houses, high-rise caged-layer houses, and narrow caged-layer houses, due to their ability to disperse to neighboring communities (for discussion of fly control and poultry housing, see Rutz [1981] and Axtell [1985]). The simplest methods for monitoring fly populations in poultry houses are sticky ribbons (Anderson and Poorbaugh 1964), baited jug-traps (Burg and Axtell 1984), and spot cards (Axtell 1970). Based on experiments conducted in an enclosed narrow poultry house where the house fly was the sole species present, Lysyk and Axtell (1985) found that fly catches in baited jug-traps and spot card indices change proportionally with real changes in house fly density, and proposed that these methods be used to monitor house fly populations in poultry houses. Legner et al. (1973) found that sticky ribbon catches of house flies and other species of flies were correlated with the numbers of flies emerging from poultry manure in narrow caged-layer poultry houses in California. Anderson and Poorbaugh (1964) found that sticky ribbons were a favorable method of surveying house fly and little house fly populations in narrow caged-layer poultry houses in California. This study was undertaken to evaluate these three monitoring methods under field conditions in three types of poultry production systems in North Carolina, particularly to determine 1) the seasonal abundance of the three fly species, 2) if baited jug-traps and sticky ribbons captured flies of each of the three major species in all poultry systems, 3) if spot card indices were related to abundance indices of the three fly species, and 4) the number of samples npeded to obtain precise relative estimates of house fly abundance. Materials and Methods An extensive data base was developed for simultaneous observations of the performance of sticky ribbons, baited jug-traps, and spot cards for monitoring filth fly populations in three poultry housing systems. Fly populations were sampled weekly for 6 months per year, the period of substantial fly abundance in North Carolina, with sticky ribbons, baited jug-traps, and spot cards in three types of poultry housing systems. Nineteen narrow (California style) caged-layer houses were sampled during a 2-year period, 10 high-rise houses were sampled during a 4-year period, and 12 broiler-breeder layer houses were sampled for 1 year. This data base allowed comparisons of sampling methods under a wide range of conditions. Due to the difficulty in distinguishing between O. aenescens and O. leucostoma, the black garbage flies were designated Ophyra spp. Narrow Caged-layer Houses. Narrow houses