1. This paper presents data gathered to check results secured during the summer of 1925 and to attempt to ascertain the causes for losses in production that resulted from spraying. 2. Exposing high producing cows to an exceedingly heavy infestation of house flies did not result in lowered production. 3. In the absence of flies, sponging with water had no effect on production, spraying, with water caused a loss of 5.4 per cent, with pine tar-creosote a loss of 6.9 per cent, and with oil a 9.7 per cent loss. 4. During the last two weeks of spraying the loss in production was 12.5 per cent for the pine tar-creosote and 22.8 per cent for the oil sprayed group. 5. The body temperature was consistently higher, sometimes as much as 3 degrees F., for the oil sprayed group than for the controls. The respiration rate of the former averaged 40 per cent higher than that of the latter.