COMPARISON OF CORE SAMPLING AND PUPAL TRAPS FOR MONITORING IMMATURE STABLE FLIES AND HOUSE-FLIES (DIPTERA, MUSCIDAE) IN BEEF FEEDLOT PENS

Core samples and cylindrical pupal traps were used to monitor immature stages of the stable fly, Stomoxys calcitrans (L.), and house fly, Mu sca domestica L., from 5 sample areas In beef feedlot pens: the feed a pron-soil interface, the back fence, the side (pen dividing) fence, ti le mound, and the general lot. One feedlot was sampled during 1986, tw o feedlots were sampled in 1987, and three samples were taken at rando m from each sample area on each sample date. Core samples showed that both populations were highest from the feed apron sample area. Pupal t raps tended to show the same result but differences between sample are as were not significant for immature stable flies. Both sampling metho ds generally indicated similar population trends of tile 2 fly species over the season; correlation coefficients between the 2 sampling meth ods were generally significant but few correlations were strong and la rge divergences between population trends were present. Only approxima te to 69% of the total number of pupal traps placed were recovered; th e loss of traps could have contributed to differences between the 2 sa mpling methods. Core sampling would be preferred if lower variance of samples is important; if collecting pupae of known age is important, t hen pupal traps may be useful if they are protected from trampling by cattle.