. Annual report - Entomological Society of Ontario. Entomological Society of Ontario; Insect pests; Insects. 48 THE REPORT OF THE Date flight Date flight Length of Actual number of Year began ended flight in days nights moths flew 1927 July 8 Aug. 7 31 25 1928 July 7 Aug. 9 34 25 1929 July 4 July 31 28 22 The actual number of nights the moths were in flight is lower than the length of the seasonal flight because on a number of nights when it was expected moths would be in the field they were absent, due, in most cases, to undetermined fact- ors. There were six such nights in 1927, nine in 1928
. Annual report - Entomological Society of Ontario. Entomological Society of Ontario; Insect pests; Insects. 48 THE REPORT OF THE Date flight Date flight Length of Actual number of Year began ended flight in days nights moths flew 1927 July 8 Aug. 7 31 25 1928 July 7 Aug. 9 34 25 1929 July 4 July 31 28 22 The actual number of nights the moths were in flight is lower than the length of the seasonal flight because on a number of nights when it was expected moths would be in the field they were absent, due, in most cases, to undetermined fact- ors. There were six such nights in 1927, nine in 1928, and six in 1929. The length of the flight season for each year is shown in the figure below:—. Fig. I. Graph Showing Flight of Com Borer Moths Laboratory Field, Chatham, Ontario 1927-1929 Inclusive The total number of moths observed during the flight season in the three years, varied considerably. In 1927, 258 moths were observed, while in 1928, 370 were observed and in 1929, only 108 were recorded. In 1927, therefore, the average number of moths captured for each night of actual flight was , in 1928, and in 1929, only The reduction in the number of moths is shown in the above graph which shows the actual number of moths caught each night for the three years. There are several factors which might cause-this reduction in the number of moths during the past two years. Any serious thought on this point admirably illustrates the compexity of our problem. Of the factors which might cause a reduction the following are probably the most important:—(1) Weather and other factors regulating the number of eggs laid, the percentage hatching and the mortality in larval establishment. (2) The compulsory farm clean-up of corn refuse. (3) The increase in the corn acreage from 1927 to 1929. We have, no means of evaluating many of these factors at the present time. It would appear, however, as if the farm clean-up and the increase in acreage were responsible for a great part
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectinsects, bookyear1872
