PROGRESS REPORT ON THE EUROPEAN CORN BORER 125 
It is very difficult to obtain exact information on the flight habits 
of the adults of this insect, especially because natural flight occurs 
at night, and what is now known concerning the detailed habits of 
flight has been obtained during the hours of daylight when flight of 
the insects is possibly somewhat abnormal. One theory concerning 
air currents that pass over a body of water is that they tend to drop 
objects that they are carrying on reaching land. This theory would 
help to explain the regularity in which early infestations on the 
southern shore of Lake Erie followed the shore line, had air currents 
or winds played an important part in this distribution of the insect. 
But even if this were true, the possibility that water drift was of 
equal importance in dispersion about the lake still exists. 
Certain of the factors that support the water-drift theory of dis- 
tribution of this insect about Lake Erie may now be considered. 
The New England Infestation 
The New England infestation is fairl}^ illustrative of the possible 
spread of the insect by water drift, particularly as applied to Cape 
Cod. The early infestation on Cape Cod was principally on the 
northern shore, or that joining Massachusetts Bay, facing the origi- 
nal New England infestation of this insect, as it has been conceived, 
and where the most severe infestation is found to-day. Had water 
* drift played no part in this infestation, it seems remarkable that 
the infestation should develop in this way. The northern shore 
is a much poorer agricultural section than is the southern part of 
Cape Cod, yet in the southern part the infestation has been slow in 
developing and is of much less intensity. The infestation here, 
then, has developed in the way that would be expected, had water 
drift played an important part in dispersion. Had flight of moths 
played an important part in this spread, it seems improbable that 
so large a proportion of them would have been able to descend so 
soon after reaching land, "but that many would have been carried 
either farther inland on the cape, or completely over it, and thence 
out to sea. In this connection it may be remarked that the distance 
that the moths would have been carried by such winds would have 
been somewhat less than half the distance from the probable original 
seat of infestation across Lake Erie. The shipment of infested vege- 
tables to summer resorts as a means of dispersion of the insect is 
often mentioned in this case, but although this factor has undoubtedly 
been of importance, it must be said that the large summer resorts on 
Cape Cod are on the south shore, whereas the important infestation 
of the insect has been found on the north shore. That infested corn- 
stalks do float out into Massachusetts Bay has been proved by several 
examinations of the islands in Boston Harbor. In 1920 a thorough 
examination of one of the larger of these islands (Inner Brewster 
Island) showed that the only infestation on the island, at that time 
was in a single plant of cocklebur which contained several larvae. 
This plant was growing on an arm of the island extending toward 
the mainland, and on which considerable quantities of refuse had 
been thrown by the sea. The following year a second examination 
of the island showed that the only larvse then present were con- 
tained in a piece of drifted cornstalk that, together with a consid- 
erable quantity of refuse, had been cast on the island, curiously 
