4 BULLETIN 787, U. S. DEPARTME]!^T 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 

 fomid 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 14 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 4 inches in diameter, 

 were left standing. None 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 na 

 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 golclenrod cover the ground on all open 

 spots. All isolated locusts are heavily infested and have been dam- 

 aged severely by the borers. Many of these trees have fallen over 

 (PL I, fig. 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 thrifty and no evidence of borers 

 can be found. They represent what can be grown in 18 years' time on 



1 The photo^aphs were taken by Mr. R. A. St. George, scientific assistant, Forest In- 

 sect Investigations, Bureau of Entomology. 



