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increases from 1939 to 1940 took place in 26 of the 35 counties surveyed in 
the 2 years, and the population trend in S other counties was in the direction 
of an increase. In 1940 populations averaged over 100 borers per 100 plants in 
each of 9 counties in the eastern part of the State, as compared with 5 counties 
in this category in 1939 • The greatest abundance of the corn borer in Indiana 
in 1940 was found in Wells County, where there were 343*6 larvae per 100 plants; 
the 4 next most heavily infested counties — Blackford, Jay, Adams, and Allen — 
had populations per 100 plants of 263 . S, 252 , 6 , 246.4, and 234,5, respectively. 
One of the most important increases from 1939 to 1940 appeared in Wayne County, 
in the southeastern part of the State, where the average number of borers per 
100 plants increased from 3*1 i n 1939 to 101,7 in 1940. 
Ohio , — In a section of northwestern Ohio, comprising 31 counties, the corn 
borer increased significantly in numbers from an average of 103.5 larvae per 100 
plants in 1939 to 227 in 1940, Thirteen counties in the section showed signi- 
ficant increases in borer abundance from 1939 to 1940, while all but 1 of the re- 
maining IS counties displayed a trend toward increase in the same period. Popu- 
lations wore much higher in 1940 than in 1939 i n a number of counties. Tan Wert 
and Hancock Counties in 1940 had the highest averages found to date in Ohio — 
453 and 427.6 borers per 100 plants, respectively, while Paulding, Putnam, 
Hardin, Auglaize, Fulton, and Wyandot had populations per 100 plants averaging 
393*6, 391*2, 379, 367 . 6 , 350.4, and 309 . 6 , respectively. In other words, S of 
the 31 comparable counties, or 25 . S percent, averaged more than 3 OI borers per 
100 plants in 1940. Only 1 county out of the same group was infested to that 
extent in 1939. Ten other Ohio counties in 1040 each averaged 201 to 300 borers 
per 100 plants, and 6 more had populations of 101 to 200 larvae per 100 plants. 
In 1939, 45.2 percent of the 31 comparable counties averaged more than 101 borers 
per 100 plants, whereas in 1940 the percentage of counties with populations of 
this size was 77*4. Infestation by the borer in 8 counties in the southwestern 
corner and 4 in the southeastern part of the State, surveyed in 1940 only, was 
relatively light, 
Michigan . — Within a section composed of 20 counties in southeastern Michi- 
gan, there was an average of 244.1 larvae of the European corn barer per 100 
plants in 1940, as compared with 210.5 in 1939* Significant increases from 
1939 to 1940 occurred in the counties of Sanilac, Macomb, Saginaw, and Living- 
ston, while pronounced decreases were noticeable only in Ingham and Washtenaw 
Counties. High populations continued to bo chronic in the northern portion of 
the . 11 thumb , 11 where each of 10 counties averaged more than 200 , and each of 7 more 
than 300 borers per 100 plants in 1940, including Gratiot and Sanilac Counties 
with maxi mums for the section of 516.2 and 512 borers per 100 plants, respective- 
ly, The last 2 counties mentioned were the most heavily infested of any sur- 
veyed in 1940 in the Michigan— Ohio-Indiana area. Five other counties surveyed 
in Michigan in 1940 had 101 to 200 borers per 100 plants, while the remaining 
5 , all in the southwestern part of the section surveyed, averaged less than 73 
borers per 100 plants. 
Pennsylvania . — With the exception of observations in Bucks County on the 
southeastern border of Pennsylvania, the 1940 survey was confined to the' western 
half of the State and to counties from most of which no data on corn borer 
abundance had been obtained for some year's. In 30 such counties surveyed in 
