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JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 17 
or limit serious injury to valuable crops such as seed corn, early sweet 
com, flowers and vegetables, the best results were secured with nicotine 
dusts (F 2 and F 4 ) or with dusts in which nicotine was an ingredient 
(70 Lime, 10 Sulphur, 10 Calcium arsenate, 10 F 2 ). Lead arsenate and 
calcium arsenate combined in various proportions as a dust with sulphur 
and lime failed to give any encouraging results the first season. Calcium 
cyanide, in the preliminary experiments, seriously checked the growth 
and burned the young corn plants. Nitro-benzol incorporated into a 
dust gave encouraging indications as an ovicide and also proved toxic 
to the young larvae on contact. None of these substances can be 
recommended, however, in their present development since the maximum 
percentage of control secured was 83% for the ears and 88% for the stalks, 
while the cost of the experimental treatment varied from $5.68 to $31.80 
per acre; approximately $9.00 per acre for the most successful treat¬ 
ment. 
Winter Mortality 
The investigations relative to winter mortality in New England 
during the past four winters have shown an average annual mortality 
attributable to this cause, of approximately 8.5%. This figure relates 
to larvae which passed the winter under natural conditions, and is ex¬ 
clusive of parasitism and feeding by birds. Judging from results to date, 
it is not believed that winter mortality is an important factor in reducing 
the larval population. During the winter of 1922-1923, however, the 
winter mortality, in experimental material placed along the northern 
border of the infested area in Maine and New* Llampshire, varied from 
22% to 45%. This may be indicative of a certain measure of climatic 
control during some winters in this northern area, a point which it is 
hoped can be determined by additional observations each year. 
The winter mortality in New York and Ohio has averaged less than 
one per cent each year in the material under observation. 
Feeding by Birds 
Birds have been exerting an increasingly important influence each 
year since 1919 in reducing the numbers of overwintering larvae. From 
a series of 20 special observation stations which were nfaintained in 
New England, during the winter of 1922-1923, birds were found to have 
taken 72.2% of the larvae in five of the stations, less than one per cent 
in three of the stations and none in the remaining eleven stations. 
Woodpeckers, especially the Downy Woodpecker (Dryobates pubescens) 
were usually responsible for this beneficial activity, although robins, 
