PBOGEESS EEPOET OX THE EUROPEAN COEX BOEEE 
139 
cessfully passed the winter of 1923-24. A few cocoons of M. 
tibialis were also recovered during 1924 under circumstances which 
indicated that this species had passed at least one generation in the 
field since liberation in its new environment. 
It is proposed to continue the large-scale rearing in the laboratory 
and liberation in the field with each of the parasitic species, for 
which a satisfactory rearing technic can be developed, supplemented 
by extensive collections abroad of the species which can not be suc- 
cessfully or economically reared in the laboratory. It is problem- 
atical, of course, whether any of these species will become perma- 
nently established in this country, and several years may elapse before 
the results will be definitely known. 
PREDATORS 
BIRDS 
In the late winter and spring of 1922 as high as 95 per cent of the 
larvae were removed from standing cornstalks in some of the small 
home gardens in the environs 
of Boston, presumably by wood- 
peckers. Their beneficial activi- 
ties were also noted in many 
widely separated localities in the 
Xew England area, and to a lesser 
extent in Xew York State. From 
10 cornstalks used in one particu- 
lar hibernation experiment at Ar- 
lington, Mass., 160 larvae out of 
a total of 200 (80 per cent) were 
removed from their burrows by 
birds during this period. A 
downy woodpecker (Dryobates 
'pubescens Linn.) was observed 
drilling into these cornstalks and 
removing the larvae. Judging 
from the character of the holes 
made in the cornstalks by this 
individual in its search for the 
larvae (fig. 52), it seems probable 
that this and allied species may 
be credited with much of the work 
mentioned previously. Prior to 
1922 only occasional instances of 
similar work in infested corn- 
stalks had been observed. Ac- 
cording to Barber (6), from a 
series of 20 special observation 
stations which were maintained at 
widely distributed points in Xew 
England during the winter of 
1922-23, birds were found to have 
taken 61 per cent of the larvae in 
five of these stations, and the remaining 
Fig. 52. — Cornstalks from which European 
corn borer larvae have been removed by 
birds, probably the downy woodpecker. 
Medford. Mass.. April 13. 1922 
recovered in good condition exhibited little or no feeding b} 
13 stations which were 
birds. 
