18 BULLETIN 1426, U. S. DEPARTMENT OF AGRICULTURE 
certain days. As many as 497 beetles were counted on the east side 
of the west screen on May 31. These were caught in the period from 
May 24 to the date of examination. The maximum temperatures, 
at Forest Grove, 2 miles west, were 60°, 57°, 64°, 71°, 75°, 75°, and 
68° F., on the days preceding the count. In the same season the 
screen illustrated in Figure 8 was erected in the sagebrush near Wa- 
pato, Wash. This screen was located at least 114 miles west of land 
under irrigation and 2 miles from the nearest clover field. On 
May 22 one root borer was found on this screen, indicating that this 
beetle had flown as far as 2 miles from the nearest clover, which was 
probably the only possible source from which it could have come. 
The experiments with flight screens therefore indicate that root 
borers may fly as high as 50 feet and possibly as far as 2 miles. The 
large numbers caught on small screens indicate the tremendous num- 
bers of beetles flying simultaneously on favorable days, especially 
from clover fields which have been plowed in thespring. <A study of 
these flight data leads to the conclusion that the grower can, single- 
handed, do little to control this pest. Only by community action 
can control be attained. 
EGG BURROWS 
Shortly after the first spring flight, root borer adults are found in 
short new burrows in the roots of clover of the preceding year’s 
seeding or in new mines on older roots. Burrows containing early 
egos and females are found in the latter part of April and commonly 
in the month of May. Often two adults, male and female, are found 
in one egg gallery, so that it is evident that the males have lost no 
time in following the females to new host plants. Rarely two females 
are found together in one egg gallery, and in such cases the usual 
number of eggs in this common burrow is doubled. Unattached 
males are found feeding in superficial grooves and burrows on the 
clover crowns. 
Toward the end of May or the beginning of June egg galleries, 
containing usually four to six eggs, are found abandoned by the adult 
borers. The earliest laid eggs at this time are found hatching mi- 
nute, first-stage larve. New and apparently recently started mines 
are then found in considerable numbers on clover roots, and it seems 
safe to assume that in some cases the parent borers have changed 
roots or at least burrows. This assumption is strengthened by the 
observation that a single female in a cage placed over several clover 
plants formed egg mines in and infested more than one root. Some- 
times four out of five roots in the cage were thus infested. Indica- 
tions have been noted that possibly one or two other changes are 
made by some borers in the field. New burrows have been found in 
the last week of June and about the middle of July. Some of these, 
however, may be attributed to belated adults which overwintered 
as larve. 
Egg galleries made in June and July are shorter than those of May, 
and the eggs are usually more numerous and closer together than in 
the earlier egg burrows. True pairs of adults are often found in 
these mines—in 1916 even as late as July 22. Adults, however, be- 
come fewer and fewer as the season progresses, so that by July old 
beetles are rarely found. Dead adults seldom are found in egg gal- 
eta see ed Be oy I De 
