- 12 = 
In connection with studies of parasites of the beet leafhopper 
(Eutettix tenellus Baker) by C. F. Henderson and assistants at Twin Falls, 
Idaho, P. N. Annand says: "It is of interest to note that the percentage 
of parasitism of male E. tenellus was greater than that indicated for the 
females, the size of the parasites in the two sexes being practically the 
came." 
In regard to egg parasites, Mr. Annand states: "Dissections of a 
large number of E. tenellus females indicated that on September 11 there 
were practically no mature eggs within the ovaries. This has an important 
bearing on the life history of egg parasites, for it is evident that eggs 
of the overwintering host could not have been deposited after this date." 
Migratory movements of the beet leafhopper have been the subject of 
study at Davis, Calif. William C. Cook says that on October 27 he "wit— 
nessed a migration of tenellus into the mouth of Big Panoche Pass. The 
bugs were coming in in large numbers at sunset and were travelling slight— 
ly west of south on a light breeze from the north. The wind movement was 
about 200 feet per minute. Mr. Romney also witneSsed a Similar migration 
near the mouth of Hospital Canyon on October 24; in this case, also, the 
bugs were flying with the wind. It is quite noticeable that on days when 
many bugs were moving there was a very light wind movement, and generally 
in the western side of the valley this wind movement comes from slightly 
east of north, undoubtedly due to deflections of the general wind currents 
by the mountains on the east side of the valley. All our evidence tends 
to indicate that the fall migration is a general southward drift and that 
the finding of the canyons is more or less accidental. As these canyon 
mouths are practically the only places on the western side of the valley 
where the vegetation is green, the bugs concentrate on these areas." 
FOREST INSECTS 
Ralph C,. Hall, Columbus, Ohio, reporting on investigations of the 
locust borer (Cyllene robiniae Forst.) says: "An analysis of these data 
so far has demonstrated that a very close relationship exists between site 
and injury by the locust borer. When based upon site index? the relation— 
ship is an inverse one, the higher the site index the lower is the amount 
of injury. This confirms the opinion formed from general observations 
during the collection of the data. There appears to be a definite re— 
lationship between crown class2 and injury by the locust borer. Age af— 
fects this relationship, however * * * Up to ten years of age the re— 
lationship between crown class and injury is as follows: the dominant 
class shows the highest percentage of injury, followed by the codominant, 
1 "Site index" refers to the quality of the environment in which 
trees are growing. There are several site qualities used to desig— 
nate the comparative volume increment in a stand of timber over a per-— 
iod of years. Frequently five classes are used. . 
2 "Crown class" refers to the position of the crown of the tree in 
the forest canopy. "Dominant" trees are those that have their crowns 
highest; "codominant," "intermediate," and "overtopped" are decreasing 
grades. 
