Sept. 15,1925 
Distribution of the Golorado Potato Beetle 
547 
unsprayed cultivated field of the same variety. The subsequent 
history was a severe infestation of the Cobbler field by the adults of 
the first brood, although the writer found that many of the adults 
had remained on the volunteers. Figure 1 is a photograph of these 
two fields showing their adjacent relation. 
The foregoing refers specifically to conditions prevailing in northern 
Maine. 
In western New York, sufficient data are lacking to establish 
definite relations between the presence of volunteers and infestation. 
The writer has found volunteer potato plants in wheat fields and 
their presence there has been noted by growers, but in the season of 
1924 they were so few in number, their size so small, and their infesta- 
tation so light, that no importance could be attributed to them. 
Whether the season of 1924 was normal in this respect was not 
determined. 
In regard to control, the writer has noted that spraying oat fields 
with iron sulphate has not materially reduced the number of volun¬ 
teers, and he does not at this time attempt to suggest a means for 
their eradication. Consistent crop protection by means of arsenicals 
and farm practice heretofore considered is, of course, indicated. 
SUMMARY 
Although great progress has been made in the development of 
artificial methods for the control of the Colorado potato beetle 
(.Leptinotarsa decemlineata ), the insect is a persistent and expensive 
annual pest. Little attention has been centered on methods of pro¬ 
tecting the potato crop other than the use of the arsenical stomach 
poisons. 
Certain variable factors operate in a northern latitude to cause a 
variation from farm to farm, or from field to field, in the percentage of 
infestation of the beetle. 
A study of infested potato fields in western New York and northern 
Maine indicates these variable factors to be the height of the culti¬ 
vation ridge, the nature of the previous crop, the earliness in the 
appearance of the shoot above ground, the deterrent effect of the 
early sprays, and fluctuations in the numbers of volunteer potato 
plants. 
Farm practice with these factors in mind is recommended. 
