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Table 1, A 12-year comparison of avera e European corn borer populations 
in 18 comparable counties—/ of Michigan and Ohio, 1927-38 
; Average borers , : 
Year per 100 plants-/ : 
; Year 
Average borers 
■per 100 plants—' 
: Humber : 
1927 ; 21.3 : 
1928 : 17.1 ; 
1929 : 32.7 : 
1930 +17.3 . : 
1931 • + 4o.7 ' " *: 
1932 ; 4s.'6 : 
! 1933 — 
; 1934 
; 1935 
: 1936 
: '1937 
J_1338 — — 
Humber 
U 5.5 
+ 15.6 
• ±42.4 
. ,+69.9 
• +99.0 . 
£129.3 
If 
2 / 
The counties involved are the same as those surveyed in Michigan 
and Ohio in 1938 and listed in. table 2. 
♦Indicates significant decrease; vindicates significant increase. 
The data obtained in the 1938 fall survey are presented in table 2, to- 
gether with comparable data for 1937 * The most important , features '.characteriz- 
ing the known abundance of the European corn borer in 1938,. as determined by V 
this survey, may be summarized briefly as follows; 
(1) An increase of corn borer populations in the counties of Williams.,. 
Defiance, Paulding, Fulton, Henry, and Hancock, in northwestern Ohio, .to numbers 
above any previously recorded in that section of the State. ......... 
(2) The maintenance of borer abundance at approximately the same level 
as in 1937 in the Ohio counties of Lucas, Wood, Putnam, Seneca,, and Sandusky, ■ 
and a decrease from 1937 in Ottawa County, Ohio. 
.* 
(3) A significant decrease from 1937 in the counties of St. Clair, Wayne, 
and Monroe, in southeastern Michigan, with no change in Macomb, Washtenaw, and 
Lenawee Counties, Mich. However, toward the southwestern portion of the Michigan 
section, in Lenawee County, the occurrence of highly infested fields was more 
general than in other years of survey. 
< (4) An increase of a character similar to that in northwestern Ohio 
extending westward into 10 counties of northeastern Indiana, where populations 
were higher than found in any previous survey in this region, and the more exten- 
sive occurrence of the borer over most of the remaining territory infested in 
that State. 
( 5 ) fhe presence of higher infestations than in previous ye.ars in the 
county groups of Jeff ers ^n— Oswego and Chautauqua— Erie— Niagara in western Hew 
York. 
(b) A rapid rise in infestation by the second generation of the borer in 
central Hew Jersey resulting in some of the highest populations in field corn yet 
observed in the United States, with notable increases over 1937 in Monmouth, 
Middlesex, and Burlington Counties, 
