148 BULLETIX 1476, U. S. DEPARTMENT OF AGRICULTURE 
the severe corn-borer infestation/' By the close of 1925 the course 
of the infestation had progressed so that in Kent and Essex Counties 
the crop throughout at least 400 square miles was completely ruined. 
Control measures were adopted very slowly by growers, as there 
existed no legislation requiring their adoption. This situation 
culminated during 1926, when it was found that throughout an 
area of 1,200 square miles the corn acreage had been reduced to 10 
per cent of the land devoted to that purpose in 1922. In this area 
of intense infestation many fields showed a loss of the entire crop 
and losses of 75 per cent were common. Legislation requiring corn 
growers to clean up their fields became effective October 1 of that 
year. In the meantime the infestation in Canada had progressed 
eastwardly, completely surrounding Lake Ontario and joining with 
the infested area in Xew York, which had made progress along the 
southern shore of the lake. Distribution surveys in southern and 
central Europe have demonstrated the presence of the borer in prac- 
tically all areas where corn and other susceptible crops are grown. 
HOST PLANTS 
Xo change has occurred in the status of corn as the preferred host 
of the European corn borer in America, since in all areas it continues 
to be more generally infested and sustains more serious injury than 
any other plant attacked. 
In the middle western areas a light infestation has developed in 
several of the more susceptible weeds and field crops when such 
plants were associated with badly infested corn. Xo severe economic 
injury, however, to crops other than corn has occurred in these areas 
to date. The corn borer has been found infesting a total of 46 species 
of plants (principally large succulent weeds) in western Xew York, 
18 species in Ohio, and 8 species in Michigan. The plants of most of 
those species function primarily as shelter plants rather than as true 
food plants. 
In Xew England a total of 224 species have been recorded as hosts 
' of the corn borer. In those species are also included all of the west- 
ern host species. Of the total number of species not more than 38 are 
known to constitute true food plants. The severity of the infestation 
in vegetables, field crops, flowers, and weeds has decreased in Xew 
England during 1925 and 1926 as a phase of the general reduction in 
the importance of the insect as a juest in that region. 
EXTENT OF INJURY AND ECONOMIC LOSS 
In Michigan, Indiana, Pennsylvania, and Ohio, with the exception 
of a few fields in northwestern Ohio, there has been very little 
economic loss caused by the corn borer to the close of 1926. In 
western Xew York, however, the estimated commercial loss exceeded 
25 per cent in certain dent cornfields grown for grain in the older 
portion of the infested area, while the loss in sweet corn ears for 
canning in 1926 reached approximately the same figure (24.8 per 
cent ) . 
The widespread dispersal of the pest in this entire Lake Erie-Lake 
Ontario region during 1925 and 1926 was accompanied by an increase 
in intensity of infestation which amounted in 1926 to approximately 
