Yearboo^ of Agriculture 1949 



of beetles and moths. Their larvae 

 cause injury by tunneling into the sap- 

 wood and heartwood of the trunks. 

 The locust borer, which attacks black 

 locust, is a good example of this group. 



The twig borers and girdlers consist 

 principally of certain roundheaded 

 beetles, the larvae of which mine or 

 girdle the terminal shoots. Sometimes 

 the girdled terminals are not entirely 

 broken off by the wind; then dangling 

 dead branches become conspicuous, 

 especially on hickory and oak trees. 



The white-pine weevil attacks and 

 kills the leaders of white pines. 



A moth causes similar injury to the 

 terminal shoots of the red and Scotch 

 pines. 



The elm bark beetles feed in the 

 crotches of the smaller branches of the 

 elm tree and, in doing so, transmit 

 the spores of the destructive Dutch elm 

 disease. 



Certain sucking insects, known as 

 chermids, attack the terminal shoots 

 of white pines and frequently cause 

 a marked drooping of the branches or 

 their death. 



The buds of several species of pines 

 are subject to attack by tip moths. 



The gall-making insects consist for 

 the most part of tiny flies, certain plant 

 lice, small wasps, and some mites. Most 

 of them are relatively unimportant. 



The leaf feeders include nearly all 

 types of insects and their close relatives, 

 the mites; the chewing insects destroy 

 the foliage and the sucking insects 

 remove the juices. Some mine the 

 leaves; others work on the surface. 



The elm leaf beetle and the Japanese 

 beetle are good examples of the leaf- 

 eating type. They skeletonize the foli- 

 age and cause the leaves to turn brown 

 and drop to the ground. Repeated de- 

 foliations weaken elms and may cause 

 their death. 



Of these two insects, the Japanese 

 beetle is by far the more important 

 economically. Unchecked by its natu- 

 ral enemies and supplied with an abun- 

 dance of its natural food plants, it soon 

 spread over much of the eastern United 

 States. Serious infestations now occur 



from Connecticut to North Carolina. 

 The beetles appear during June and 

 remain active until the latter part of 

 August in the vicinity of Washington, 

 D. C. They cause most extensive in- 

 jury during the first 2 or 3 weeks, when 

 they attack the upper and outer parts 

 of trees and shrubs exposed to sunlight. 

 The beetles also can seriously injure 

 flowers, fruits, vegetables, and the 

 grubs destroy the roots of grass and 

 other plants. 



The catalpa worm, or sphinx, is an 

 example of the kind of insect that eats 

 the entire leaf and frequently all the 

 leaves of a tree. 



The bagworms attack many kinds 

 of trees. Their favorite host is arbor- 

 vitae. Their presence can be detected 

 by the cases or bags on the trees. 



The locust leaf miner is a small, 

 brownish beetle that deposits its eggs 

 on the leaf surface. The new-hatched 

 larva penetrates the leaf and mines the 

 interior. Severe injury disfigures the 

 leaves and may kill them. 



Spider mites and such insects as the 

 aphids, chermids, and scales suck the 

 juices from the foliage of many kinds 

 of shade trees. One leafhopper that 

 feeds on elm leaves has been found to 

 transmit the elm virus disease, which 

 kills the trees more quickly than the 

 Dutch elm disease. 



GENERAL PRECAUTIONARY MEASURES 

 can do much to prevent such insect 

 damage to shade trees. Some, which do 

 not require the use of chemicals, are 

 aimed at safeguarding the trees from 

 the weakening influences to which they 

 are frequently subjected during and 

 following new construction. 



Trees that are being left to provide 

 shade about new residences, after thin- 

 nings have been made among the re- 

 maining trees, should have their trunks 

 wrapped with burlap or other suitable 

 material to prevent sunscald in hot 

 weather. 



Isolated tall trees of small diameter 

 should be anchored by guide wires to 

 keep them from being whipped by the 

 wind. 



