584 
JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 17 
The northeast side of this cultivated area was bordered by a row of 
willow trees some 20 feet from the edge of cultivation, the intervening 
space being in grass. Along this edge (358 feet) three traps were placed 
about 15 feet from the edge of cultivation. In these three traps a total 
of 109 larvae were recovered during the whole period of observation indi¬ 
cated above, the greatest number in the three traps for any one night 
being 29 and the greatest number in one trap one night being 19. The 9 
feet covered by these traps is but a very small fraction of the total dis¬ 
tance along this side of the field, so that from these indications it may be 
safe to say that a considerable number of larvae moved out of the culti¬ 
vated area and sought some location other than the food plant in which to 
spend the winter. 
In overwintering cages placed for the purpose of observing whether the 
larvae of this insect were able to successfully pass the winter in sod, 13 
pupal cases from which adults had issued in the spring were found in 
rolled up maple and elm leaves. A total of 50 larvae were introduced into 
these cages in the fall. This is a significant point in connection with the 
extensive migration described above. 
About a quarter of a mile from the plot previously described there is a 
small area of bog which in the summer of 1922 had grown up to a nearly 
pure stand of Polygonum sp. and these plants, common hosts of the in¬ 
sect, were well infested with larvae. Along one side of this bog on rising 
ground there is a row of old apple trees. 
Towards the middle of September of this year it was observed that 
windfall apples under these trees were riddled by larvae of the European 
corn borer. Investigation and recovery by the use of migration traps 
showed that the larvae were migrating in great numbers from the poly¬ 
gonum and were moving towards higher ground either in search of fresh 
food or of hibernating quarters. The condition of the windfall apples 
showed that they had satisfied the first mentioned desire while on ex¬ 
amination of the trees showed that some of the larvae at least had taken 
refuge there Under the rough bark, in cells not unlike those in which 
larvae of tht i ,dling moth spend the winter, the corn borer larvae were 
found in some numbers and others had penetrated the rotten wood of 
stumps that remained after limbs had been removed. Subsequent ex¬ 
aminations through the winter and following spring showed that not 
only did larvae spend the winter under the bark but that they pupated 
and adults emerged, the live pupae and empty pupal cases from which 
adults had issued being recovered from cells under the bark. From 
previous experiments it is known that the burrowing of larvae into 
