1934] The European Corn Borer on Long Island 215 
proved to be of the one-generation strain. In 1927 four 
townships (Southold, Shelter Island, Southampton, and 
East Hampton) at the extreme eastern end of the Island 
were found to be infested with the two-generation strain of 
the borer. The Bureau of Entomology, by establishing a 
field laboratory on the Island, took immediate advantage of 
the opportunity thus presented of studying the two strains 
of this pest simultaneously in the presence of extensive corn 
acreages and in a situation more or less typical of a large 
area along the Atlantic seaboard. The principal objective 
of this project, which was carried on in cooperation with 
the Bureau of Plant Quarantine, was to ascertain the sources 
of residual overwintering borer population that would form 
the nucleus of the reinfestation in the following spring. 3 In- 
cidentally much information of a varied character was ob- 
tained which has led to a better understanding of the insect. 
The easterly dispersion of the one-generation strain of 
the borer from the site of the original colony at the extreme 
western tip of the Island has been slow indeed. During the 
decade of its existence there the borer has invaded an aver- 
age of only 4 miles of new territory each year. This seems 
a comparatively slow spread when the nature of the terrain, 
the general direction of the prevailing winds, and the abun- 
dance of corn are considered as factors exceptionally favor- 
able for dispersion. Among the probable factors restrain- 
ing a more rapid spread may be mentioned (1) the efforts 
at eradication practiced in this area from 1923 to 1928, in- 
clusive, by the Bureau of Entomology in cooperation with 
the State of New York; (2) the absence of field corn on that 
end of the Island, which limits hibernating quarters for the 
borers ; (3) the fact that the one-generation borer rarely at- 
tacks weeds, which also limits hibernating quarters; and 
(4) the fact that in this district, where considerable early 
sweet corn is grown for metropolitan New York markets, 
many of the cornfields are plowed under as soon as the ears 
have been harvested (while the stalks are still green and the 
corn borer larvae within are in the immature feeding stages) 
preparatory to the planting of fall crops. 
3 The results of this investigation have been summarized in an un- 
published manuscript by R. E. Kimport. 
