12 Farmers’ Bulletin 1294. 
it makes the best of this opportunity. It should be understood also 
that the infestation of the pest throughout even this old and in- 
tensely infested region is not uniform but that the more heavily in- 
fested areas occur in spots more or less scattered. No fields of dent 
corn are grown commercially in this area. . 
Although a very small amount of flint and no dent corn 1s grown 
for grain within that portion of Massachusetts where the corn borer 
has existed for at least a decade and become well established during 
that time, both types of corn are readily attacked by the borer, 
judging from observations made in the few commercial fields of flint 
corn available and the experimental plats which contained represen- 
tative varieties of both dent and flint corn. The experimental plats 
in which this corn was grown were situated in three different sections 
of this heavily infested region, and it is believed that the results 
there obtained represent average conditions of infestation and in- 
jury which may be expected to occur in similar localities where 
the insect is fairly abundant and has become well established. 
In this heavily infested area it was found that slightly more than 
four-fifths of the ears of flint corn (Figs. 9, 10) were infested with the 
borer, with a damage to the grain on these infested ears amounting to 
approximately one-eighth of the grain produced. Dent corn grown 
experimentally within this same area was found to be somewhat less 
injured by the attack of the borer, approximately three-fourths of the 
ears being infested, while only 2 per cent of the grain was found to be 
damaged. Sweet corn (Fig. 11) grown in this area and representing 
average conditions was found to be infested to such an extent that 
slightly more than half of the ears contained the borer at the time 
of picking, while in many of the smaller and more intensely in- 
fested fields every ear was found to have the borer present. Although 
the grain on many of the infested sweet-corn ears was only damaged 
to a slight extent, this slight injury was sufficient to render the ma- 
jority unfit for market purposes and in consequence of this injury 
there resulted an average loss of slightly more than one-third of the 
total value of the crop in 16 of the more heavily infested fields. 
The infestation and injury to sweet corn and to early maturing 
varieties of flint (field) corn in practically all cases have been more 
severe than in the larger and later maturing varieties of dent (field) 
corn. In some instances, however, the insect appeared to exhibit an 
equal preference for sweet, flint, and dent corn. In these cases the 
choice apparently depended more upon the stage of development of 
the plant, or upon its proximity to infested weeds or other plant 
material, than on the type of corn. 
During 1921, which was an unusually favorable season for cater- 
pillar enemies of corn, the resulting damage by the corn borer was 
somewhat increased over the preceding season, more markedly, how- 
ever, in towns situated at some distance from the center of the infes- 
tation, and it may be of interest at this point to illustrate by a spe- 
cific example the representative conditions which existed in the most 
heavily infested fields of sweet and field corn. In a very heavily in- 
fested 1-acre field of Longfellow flint corn, every stalk of corn in the 
field contained the borer, with an average of 11 borers to the stalk. 
The ears were nearly as highly infested as were the stalks, 96 per 
cent containing borers, with an average of 3 borers to each infested 
ear. 
