April, ’18] 
MAXSON: PEMPHIGUS BETME DISTRIBUTION 
231 
time the application is made. Effectiveness in codling moth control 
rapidly decreases at the end of twenty days. Egg hatching activity, 
on the other hand, under normal conditions, is usually approaching its 
height ten to twelve days following the hatching of the first eggs. At 
this time, then, a maximum need for protection is demanded and the 
effectiveness of the application of spray is rapidly decreasing. A large 
percentage of the losses that result and poor control obtained on the 
part of orchardists can be traced to this source. 
The reduction of time of application of a spray to the shortest safe 
period preceding egg hatching will only be productive of good results. 
Very close timing, in the case of protracted egg hatching, will often 
save an extra application of spray and much unnecessary expense. To 
accomplish this end it is necessary to obtain a very intimate knowledge 
of the insect’s seasonal behavior and demands a careful investigation in 
the different sections by a thoroughly competent investigator. 
It is the belief of the writer that the losses due to the activities of the 
codling moth in the Northwest can only be reduced to the minimum 
through the establishment of observation stations in the widely sep¬ 
arated apple growing sections. An investigator located in some of 
these sections during the past year could have saved his community 
enough to maintain a station for at least twenty-five years. 
SOME FACTORS INFLUENCING THE DISTRIBUTION OF 
PEMPHIGUS BETM DOANE IN BEET FIELDS 
By Asa C. Maxson, In charge of Insect Investigation , The Great Western Sugar 
Co., Longmont, Colo. 
The sugar beet root-louse, Pemphigus hetce Doane, presents one of 
the most serious insect problems which confront the beet sugar industry 
i 
of the Western States. 
The seriousness of this insect’s injury immediately becomes apparent 
when we realize that the difference between the sugar actually produced 
and what could be produced from the same acreage, were it possible to 
prevent this injury, amounts to a loss of several hundred thousand 
dollars annually to the industry. 
In the course of his work with this insect, the writer has been con¬ 
tinually impressed by the fact that our knowledge of the factors opera¬ 
tive in its dispersion and distribution in the sugar beet growing areas of 
the west is altogether inadequate. This led to the making of a prelim¬ 
inary field survey during the growing season of 1916, it being hoped that 
something might be learned that would eventually result in the develop- 
