4 BULLETIN 787, U. S. DEPARTMENT OF AGRICULTURE. 
same age are growing here. These trees are gnarly, some broken off, 
and all heavily infested. In the spring of 1918, 10 to 35 larvae were 
found in each of these trees. The cattle have kept down the weeds 
and underbrush which would otherwise protect the trunks. 
3. In the same general locality, about one-half mile north of these 
tracts, lies an abandoned field covered with an almost pure stand of 
virgin scrub pine 12 to 11 years old. Mixed in this pine are quite 
a few locusts. During the winter of 1915-16 about an acre of this 
pine was cleared. The locusts, then averaging 1 inches in diameter, 
were left standing. Xone of the trees were infested, as were none of 
those in the midst of the remaining pine. All were straight, naturally 
well-pruned, thrifty trees. In the fall of 1916 these trees were at- 
tacked by the beetles, and many larvae were found in them in the 
spring of 1917. The land has not been cultivated, so that a dense 
growth of weeds conceals the trunks for 6 to 8 feet above the ground. 
Scarcely any adults were found on these trees in the fall of 1918, and 
very few larvae are expected in the spring of 1919. 
In January, 1918. another part of this pine wood was cleared, 
leaving 15 trees exposed. In July the trees were examined and no 
borers found nor any evidence of injury in the past. During August 
and September, 1918, adults were observed ovipositing on these trees. 
4. Another abandoned field on an easterly slope contains a clump 
of about a hundred small locusts, 2 to 6 inches in diameter, grouped 
about several large trees. These are closely spaced, averaging 2 feet 
apart. They are well mixed with sumac, tulip, and sassafras. In 
the surrounding field are many isolated trees. All these isolated 
trees are scrubby and badly infested by repeated borer attack, while 
those in the dense clump are tall, thrifty, and contain no borers or 
defects from past injury. 
5. Another abandoned field one-half mile north of Green Gables 
station on the Washington and Virginia electric line contains several 
groups of locust from 6 to 18 years of age and many isolated trees. 
This field contains about 100 acres. Clumps of sassafras and pine 
mixed with locust and persimmon occupy much of the remaining 
area. Broom sedge and goldenrod cover the ground on all open 
spots. All isolated locusts are heavily infested and have been dam- 
aged severelv by the borers. Many of these trees have fallen over 
(PL I, fig. I). 1 Three excellent stands of locust occur here; one 
group of an almost pure stand is composed of trees 25 to 30 feet high 
and 6 to 8 inches in diameter. They grew very close together and 
have now thinned out to an average of 10 feet apart. There are more 
than 500 trees in this plot ; all are thrif tj and no evidence of borers 
can be found. They represent what can be grown in 18 years' time on 
1 The photographs were taken hy Mr. EL A. St. George, scientific assistant, Forest In- 
sect Investigations, Bureau of Entomolog3". 
