REPORT OF THE STATE ENTOMOLOGIST I918 51 
not all the losses can be fairly attributed to wheat midge. It is 
evident from the above figures that a serious infestation, 30 to 50 
per cent white heads, must mean a considerable reduction in the 
crop. For example, a white head 12 inches long contained 1 rudi- 
mentary kernel of rye and 8 maggots, another 32 inches long bore 
no grain and contained 12 maggots and a third, 33 inches long pro- 
duced 14 badly shrunken grains of rye and contained 19 maggots. 
In other words, the white heads are practically a total loss and when 
their number reaches 4o per cent or more it must mean a large 
shrinkage in the crop. Furthermore, this is by no means the total 
reduction since there may be a considerable shrinkage from the 
possible maximum in the other heads which, for the large ones as 
shown by the above tabulation, may approximate 4 per cent, in the 
medium ones this may range from 9.6 to 18 per cent and in the small 
ones from 10 to 31 per cent. 
The rye crop as a whole was probably not seriously reduced by 
wheat midge, though there is no doubt but that the yield of individual 
fields was considerably lower than it, should have been and perhaps 
reduced to a much greater extent than the farmer realized. Unfor- 
tunately it has been impossible to get accurate information as to 
yields from these fields and thus demonstrate the relation existing 
between .examinations of small quantities and the returns from 
relatively large areas. 
Factors affecting infestation. One of the important objects of 
the survey referred to above, was to ascertain the conditions favor- 
able to the wheat midge and if possible point out a practical method 
of reducing the probabilities of injury in subsequent years. 
It was thought by some that early wheat was less injured than later 
fields though this does not appear to be borne out either by variation 
in infestation in fields sown early or late or a difference in injury 
among the varieties grown, at least so far as the period of maturity 
is concerned. The time of sowing of winter wheat can have com- 
paratively little influence upon its ripening the following season 
because the latter is dependent more upon the weather following the 
starting of growth in the spring than upon the development of the 
plant before winter weather stops growth. There was practically 
no difference in the degree of infestation discoverable between early 
and late sown fields and, as will be shown later, the varietal infesta- 
tion appears to depend upon other factors than that of earliness 
or lateness. 
Deep plowing has been advocated as a method of controlling this 
pest and yet observations showed the insect to be as abundant in 
4 
