1924] Winter Mortality of the European Corn Borer 285 
Several of the experiments placed in the field and recovered 
are not shown in this table because birds removed such a large 
number of the larvae from the stalks that too few remained from 
which to draw conclusions. However, several areas stand out 
rather distinctly as showing considerable difference in the extent 
of winter mortality. First, an area represented by three stations 
in southern New Hampshire and Maine where winter mortality 
averaged 35.5 per cent; second, two localities in Massachusetts 
in inland river valleys where winter mortality averaged 22.6 per 
cent; third, four localities in eastern Massachusetts where mor- 
tality averaged 3.8 per cent; and fourth, five stations on Cape 
Cod where winter mortality averaged only .88 per cent . 
Observations in the spring of 1924 
In the fall of 1923 a series of experiments similar to those 
described for the previous year were placed in the field in the 
infested area of New England. As in the former instance the 
experiments were placed in the field in the fall after activity of 
the larvae had ceased and they were recovered in the spring 
before activity commenced so that the loss through larval mi- 
gration was expected to be limited to a few individuals. Each 
experiment consisted of four stakes to each of which were at- 
tached five infested corn stalks. The stations, 50 in number, 
were chosen in an attempt to represent the whole infested area 
in as fair a manner as possible. Using Arlington, Mass., as a 
center, these stations were run out in lines as far as the infestation 
was known to exist to the northeast, the north, the north by 
northwest, the northwest, the west, the southwest, the south 
and the southeast. On these stations 47 were recovered in good 
condition, 16 of which exhibited considerable feeding by birds. 
The average winter mortality of these 16 stations which were all 
located in Massachusetts was 1.7 per cent of the total number of 
larvae recovered. The extent of winter mortality is shown in 
table 5. In this table the stations are grouped in three main 
divisions similar to those into which the area seemed to be 
naturally divided the previous spring. 
