INSECT ENEMIES OF TREES AND SHRUBS 



MANY insects may be found on ornamental trees and 

 shrubs. Some are beneficial, many comparatively 

 harmless, and a few very injurious. The bene- 

 ficial insects include the common ladybeetles, sometimes 

 called ladybufi;s, the brij^htly colored maggots of certain 

 fiower Hies, and numerous small or very minute wasps. 

 The maggots of many of these wasps live in caterpillars, 

 and a number find plenty of food in the microscopic eggs 

 of certain insects. The delicate lace-winged fly is inter- 

 esting and beneficial, since it places its eggs on slender 

 stalks, a position which secures them from the depreda- 

 tions of the greedy young which destroy large numbers 

 of injurious plant lice or aphids. 



We may ignore for a time the many harmless insects 

 and study a few of the pests. Every part of a tree may 

 be attacked, including the root, the trunk, the branch, 

 the twig, the leaf, and even the seeds or fruit. The more 

 deadly enemies of trees are found among insects. Some 

 pests, when abundant, may kill trees fifty to one hundred 

 years old within a few months. Thousands of noble 

 shade trees in New York State have been destroyed by 

 insects during the past twenty years. Most of these 

 could have been protected at a moderate cost. 



Scale insects are so called because of the waxy, roof- 

 like covering protecting the legless, wingless, eyeless, and 

 almost helpless insects beneath. They are only a little 

 better than pumps attached to a living bag or sack, 

 except for the short time the young scale insects crawl 

 over limbs and foliage before settling 

 and producing the cottony growth, 

 which mats down to form a scale ancl 

 is soon followed by the loss of legs, 

 antennae or feelers, and eyes. Thi 

 scurfy scale and the San Jose sea It- 

 may be very abundant on the steiii^ 

 and branches of Japanese quince, 

 while the oyster-shell scale thrives 

 best on ash, poplar and lilac. The San Jos€ scale 



