1934] The European Corn Borer on Long Island 217 
in the early fall after the second generation larvae had be- 
come established in corn. There appears to have been a 
slow but steady increase in the borer population of the one- 
generation district from 1928 to 1933. The average num- 
ber of borers per 100 plants was 1.2 in 1928, 2.4 in 1929, 3.4 
in 1930, 13.4 in 1931, 5.5 in 1932, and 8.6 in 1933. 
In the two-generation district the average number of 
borers per 100 plants was 128.5 in 1928, 50.9 in 1929, 65.7 
in 1930, 401.9 in 1931, 394.4 in 1932, and 356.5 in 1933. It 
may be seen that previous to 1931 the infestation in Suffolk 
County was not heavy. The decided increase in numbers 
that occurred that year in the eastern half of the county, 
which has since been maintained, made it the most severely 
infested district in the entire area occupied by the two- 
generation strain of the European corn borer for the years 
1931 and 1932. To illustrate the severity of infestation a 
cornfield may suffer, an actual case in Southold Township, 
on the north fork, may be cited. In 1931 this field showed a 
100 percent plant infestation. The dissection of 10 infested 
plants, selected in accordance with a uniform method of 
sampling, gave an average of 57 borers per plant. The borer 
population of the field was therefore 5,700 borers per 100 
plants. Seventy-four borers was the maximum number 
found in a single plant in this field. Undoubtedly a number 
of factors are responsible for the continued heavy infesta- 
tion in the eastern half of Suffolk County. Not the least 
among these may be the enormous carry-over in potato 
plants of the first-generation borers, which afterward infest 
corn. Thousands of acres of both corn and potatoes are 
interspersed throughout the eastern half of Suffolk County. 
The larvae of the European corn borer have been found 
infesting 23 kinds of plants on Long Island, among which 
are vegetables, flowers, and weeds. A systematic survey of 
the Island would probably enlarge the following list of host 
plants compiled by R. E. Kimport. 
Zea mays L. (corn). 
Holcus sorghum L. (Sudan grass). 
Echinochloa crusgalli (L.) Beauv. (barnyard grass). 
Chaetochloa sp. (foxtail). 
