The European Corn Borer. 25 
The borers continue to feed at intervals until cold weather stops 
their activities, in November or early December. They remain in a 
hibernating condition within their tunnels in cornstalks, corncobs, 
weeds, crop remnants, or other hosts, throughout the winter. 
As stated, there usually are two generations annually in the infested 
area of New England, and the female moths of both generations 
deposit an average of about 337 eggs each. As about half of the re- 
sulting moths are females, it is evident that the pest is able to multiply 
very rapidly. 
The habits of some individuals of the European corn borer vary 
from the normal, and this fact should be taken into account when 
measures for the control or suppression of the insect are under con- 
sideration. 
Some of the larger borers frequently leave infested plants, or plant 
material, when such plants are disturbed, or when the infested plants 
begin to wither or decay. This is especially likely to occur: (1) when 
infested cornstalks are being collected in the field; (2) when infested 
cornstalks are left in piles or “stacks” in the field, in the barnyard, 
Fig. 21.—Adults, or moths, of the European corn borer: At left, female moth; at right, 
male moth. Not quite twice natural size. 
or under shelter, with the consequent decay or drying out of the 
plants; (3) when badly infested plants collapse and break over in 
the field; (4) when infested plants with comparatively small stems, 
such as. oats and some of the weeds, are cut while in a green condition 
with the consequent rapid withering or shriveling of the stems; (5) 
during the handling and shipment to market of infested plant prod- 
ucts such as sweet-corn ears or beets with top; and (6) when certain 
plant products, such as celery, are placed in underground pits. 
Under these circumstances the migrating borers have Fesenabitelsy 
been found boring into the crevices and walls of buildings, fences, 
posts, and other wooden objects. They also crawl underneath the 
loose bark of trees or fence posts and under rubbish, loose stones, old 
leaves, and clods of soil. Here they enclose themselves with a rough 
silken web. They have also been found in the corners and crevices of 
boxes used for shipping infested sweet-corn ears and similar products. 
Most of these borers are full grown and many of them are able to 
pupate and emerge as moths from these shelters. 
Full-grown borers have been found to pass the winter successfully 
and to develop into moths when placed in empty boxes and boxes 
containing soil, sawdust; dry manure, old leaves, or moss. 
The larger borers are able to live for at least a month without food, 
even during their active period of growth. This habit is especially 
important, as it renders the insects easily carried in infested material 
