1918 ENTOMOLOGICAL SOCIETY. 91 



are related to both temperature and humidity. He says : " Apparently there is a 

 degree of atmospheric humidity which being the most favorable to the maximum 

 speed of insect metabolism shovdd be designated as the optimum ; that this optimum 

 varies for each species, for each stage of each species, and for each stage of each 

 individual. 



It is a well-known fact that most species of Thrips and Eed Spiders are 

 more abundant, and hence more injurious, under warm dry conditions. 



The Codling Moth is an example of a common insect wliose development is 

 greatly influenced by weather conditions. Even within the limits of a single 

 state or province the rate of its development and the time of its stages are 

 influenced by latitude, by early and late seasons, by cool and warm seasons, and 

 by wet and dry seasons. The student will find in the observations of Simpson 

 in Idaho, Pettit in Michigan, Sanderson in New Hampshire, Caesar in Ontario, 

 Headlee in Kansas, Siegler and Simanton in Maine, Brooks and Blakeslee in 

 Virginia, and Forbes in Illinois much valuable data for investigations on the 

 relation of insects to climatic factors. 



FRIDAY AFTERNOON, 1.30 O'CLOCK. 



A motion picture film on " Field and Parasite Work on the Gipsy and 

 Brown-tail Moths " was shown by Prof. Burgess in the local moving picture 

 theatre. 



The use of this film was obtained by courtesy of the U. S. Bureau of Ento- 

 mology. It was followed immediately by another excellent film illustrating 

 " Orchard Spraying in Nova Scotia," shown ])y Prof. W. H. Brittain. 



THE EFFECT OF STABLE AND HORN FLY ATTACKS ON MILK 



PRODUCTION. 



A. W. Baker, 0. A. College, Guelpii. 



At the annual meeting of the Society in 1916 the writer gave a paper on 

 "Some Repellents for Stable and Horn'. Flies on Cattle." At that time the 

 question was raised as to whether or not fly attacks had any effect on milk 

 production. Accordingly during the summer of 1917 a spraying experiment was 

 carried out with milch cows in an endeavor to find the effect of fly attacks on 

 milk production, or rather the benefit to be derived from a prevention of these 

 attacks. 



Two lots of five cows were selected. Unfortunately, one cow aborted during 

 the course of the experiment, so that milk records could be kept of only four 

 cows in one lot. From July 17th to July 31st one lot was sprayed once a day 

 and the other lot left unsprayed. From Aug. 1st to Aug. 12th the lots were 

 reversed in spraying and from Aug. 13th to Aug. 25th the lots were again reversed. 

 In taking the milk records the first two or three days of each period were dis- 

 carded, leaving 10 days in which the effect on yield was considered. 



During the first period and part of the second, the cattle were sprayed before 

 the afternoon milking. During the remainder of the second period and the third 

 period spraying was done before the morning milking. 



