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As a measure of the risk for exposure to Lyme disease, we estimated the distribution of host-seeking adults of the blacklegged tick, Ixodes scapularis Say, on dairy farms in Barron County in northwestern Wisconsin. Vegetation ecotypes that were common to 18 farms that were representative of the county were surveyed by flag sampling. Tick prevalence and abundance, which were similar during fall and spring periods, were very low in farmhouse yards and forage croplands; only a single male was collected from 17 lawns. Sampling of 18 pastures with lactating cows also yielded only a single I. scapularis. In contrast, I. scapularis adults were captured in 9 of 37 samples from 18 pastures with heifers and dry cows; in those pastures, ticks were associated with woods and secondary vegetation or margins of pastures adjacent to woodlands. Blacklegged ticks were most prevalent and numerous in ungrazed woodlands; adults were captured in 27 of 53 samples on 13 of 15 farms, particularly when evidence of white-tailed deer, Odocoileus virginianus (Zimmermann), was apparent. The risk of encountering adult blacklegged ticks on dairy farms in Barron County, Wisconsin is therefore greatest in woodlands habitat. The presence of adult ticks in pastures with heifers and dry cows establishes an ecological basis for the exposure of dairy cattle to adult I. scapularis. Pastures with lactating cows, farmhouse yards, and forage croplands represent negligible risk.

Sand, gravel, sawdust, and pine shavings were used as bedding in outdoor calf hutches and compared with straw relative to the density of immature (maggot) house flies, Musca domestica, and stable flies, Stomoxys calcitrans. In 6-wk field trials, average densities of house and stable fly maggots in concrete mix sand ranged from only .3 to 1.6 and 0 to .1 maggots/L, respectively; pea size gravel bedding also strongly suppressed densities from less than .1 to .3 and less than .1 to .1 maggots/L, respectively. These densities represent reductions of 76 to greater than 99% relative to straw bedding, but both sand and gravel compacted and became soiled with calf feces, which resulted in unacceptable bedding sanitation and foul odors. Densities of house and stable fly maggots in pine shavings did not differ from those in straw bedding. Nevertheless, in sawdust bedding, maggot density was limited to averages of 1.4 to 8.3 house and 9.8 to 11.8 stable fly maggots/L; this represented reductions of 45 to 91% relative to straw. In a follow-up trial, house and stable fly maggot densities in sawdust averaged 11.3 and 43.9 maggots/L, respectively, reductions of 77 and 46%. These findings suggest that bedding calf hutches with sawdust during warm weather can be useful as an ecologically sound approach to controlling muscoid fly populations on dairy farms.

To investigate interrelations among factors potentially affecting body temperature, we observed body temperature, activity, and relative aggregation of 3 to 5 dry cows from a herd of 12 to 15 every 20 min. Ambient conditions were noted every 1 h and fly counts every 3 h. Observations during daylight for 5 d with and without shade indicated effects of shade were minimal and were extended to 24 h without shade at six weekly intervals. Cows lie down during the evening, grazed near sunrise and sunset, and alternated standing and grazing during the day. The aggregation index was greatest during periods of standing and least during grazing; however, it remained constant across periods of similar activity. Cows shifted activity from grazing to standing during periods of increased fly activity. Ambient temperatures ranging from 13 to 35 degrees C had little influence on measured variables. Body temperatures showed one to three daily dips (greater than 1 degree C) and a hysteresis pattern. Almost all dips were associated with transitions from lying to grazing. Body temperature was constant in the morning, rose to a higher level in the afternoon, and remained high until the next morning.