October, ’24] 
BARBER: EUROPEAN CORN BORER MIGRATION 
585 
wooden posts is common and that in such quarters some of the larvae are 
able to transform. 
On September 21, 1922 it was observed that a farmer at Winchester, 
Mass., had attempted to plow under a field of about M acre of very 
heavily infested sweet corn. The plowing was poorly done and the 
operation resulted in a great migration of the larvae in all directions. 
A number of plants not previously known to be attacked, were found to 
be harboring a considerable number of larvae. The first generation 
larvae of 1923, direct descendants of larvae of the fall migrating brood 
mentioned in this instance, were abundant and occasioned considerable 
damage to sweet corn in this section. This was caused probably in a 
large measure by successful overwintering of migrating larvea. 
In the spring examination of weeds it is often noted that plants that 
normally pass the winter in good condition contain many more larvae 
than could possibly have obtained sufficient food to complete growth 
from these plants, while plants which collapsed contained relatively few 
larvae altho evidence showed that many larvae had fed through the 
stalks. Thus in cocklebur (Xanthium sp.), which usually stands well 
over winter, as many as 200 individuals have been found in a single 
plant which is several times the number of larvae that could have ob¬ 
tained sufficient food to grow to maturity from a single plant. Here, 
then, is evidence of considerable fall migration not to be explained by 
any agricultural practice, but indicating a general search for more 
favorable winter quarters by larvae of this insect. 
We have shown that a considerable migration of larvae of the Euro¬ 
pean corn borer from their normal food plants to other winter quarters, 
takes place in the fall during a year of great abundance of the insect. 
If this migration occurs before the food plants are burned or otherwise 
destroyed,the effectiveness of such control measures is much reduced and 
a sufficient number of individuals may survive to cause serious infesta¬ 
tion the following year. It is interesting to know if a like movement of 
larvae takes place in the spring, for example from corn stalks that have 
remained over the winter in piles. 
On April 12, 1923 two piles of sweet corn stalks each composed of some 
100 stalks, that had remained in this condition over winter, were sur¬ 
rounded by 14 migration traps of the type previously described, the 
traps being placed about 10 to 15 feet distant from the corn stalks. 
The number of larvae that were recovered from these traps daily is 
shown graphically in Fig. 16. These piles of corn stalks were placed 
along the edge of the plot first referred to on the side near the row of 
