A comparison of sampling methods with respect to cattle-visiting Muscidae and their nematode infections.

Cattle-visiting Muscidae were sampled with a handnet from a blood-smeared Masonite panel as well as grazing heifers and dairy cows in south-central Sweden. All flies were examined in search of nematodes. Only Musca autumnalis was infected with nematodes (Parafilaria bovicola, Thelazia spp. and Heterotylenchus autumnalis). The only mixed infections found involved P. bovicola and Thelazia spp. Most M. autumnalis infected with P. bovicola and Thelazia spp. were found during the two first months of the grazing season, whereas the prevalence of specimens infected with H. autumnalis remained about the same throughout the sampling period. Musca autumnalis was caught in significantly smaller numbers from heifers (P < 0.05) than from panel and cows. The catches of nematode-infected M. autumnalis were similarly distributed. Catches of other cattle-visiting Muscidae did not differ significantly among the methods used. Handnet sampling off a panel is therefore considered to be a convenient and accurate method when investigating the abundance of cattle-visiting Muscidae and the prevalence of their nematode infections.