SHADE TREE INSECTS 5 



Thoroughness in applying a spray is very important. This requires a spray 

 outfit with sufficient power to drive the spray to all parts of the tree. Long 

 lines of hose necessitate higher pressure at the spray tank to supply the nec- 

 essary drive at the nozzle. To insure thorough and proper coverage requires 

 skill on the part of the operator. Any foliage left unsprayed on a tree is subject 

 to attack and may support a sufficient number of insects to cause serious injury 

 to the whole tree after the spray has weathered off. Unfortunately, even with 

 the best equipment and the most skillful application of the proper materials, 

 unfavorable weather may prevent proper coverage or lessen the value of the spray 

 by rapidly washing it off. 



Precautions in the Use of Insecticides. Extreme care should be used in han- 

 dling poisonous spray materials. They should not be inhaled, swallowed, or 

 allowed to get into open wounds. All equipment used should be thoroughly 

 cleaned and any unused poison should be properly labeled and stored where it 

 is not accessible to human beings or domestic animals. 



When using spreaders and stickers with poison sprays to prolong their effective- 

 ness, it should be remembered that these materials will also cause the spray to 

 remain longer on grass or other vegetation and objects under sprayed trees. 

 Children should not be allowed to play beneath recently sprayed trees nor should 

 cattle or other animals graze there. 



Certain sprays will stain painted and finished surfaces. To avoid injury of 

 this type such surfaces should be sprayed with water just before, during if pos- 

 sible, and immediately after the spray application. If the spray is applied when 

 the wind is not blowing toward such objects and due care is exercised in spraying, 

 much of the trouble can be avoided. Small objects may be covered. Auto- 

 mobiles should be removed. In California, street spraying for the elm leaf beetle 

 has been carried on at night to avoid traffic problems present during the day. 

 In addition, this procedure speeded up the work and thus reduced e.xpenses. 



Tree banding materials should be removed at the end of the season to prevent 

 girdling. 



Gypsy Moth 



Porthetria dispar Linn. 



The gypsy moth is one of the most destructive insect pests ever introduced into 

 New England. It is a native of Europe and was brought into this country about 

 1869 by a person living near Boston, Massachusetts, in connection with experi- 

 ments in silk culture. Some of the caterpillars escaped from the cages in which 

 they were confined, and from them has come the infestation which has been the 

 cause of so much damage to the woods and shade trees of New England. The 

 federal and state governments have already- spent millions of dollars in com- 

 bating it. 



The caterpillars have quite definite food preferences. Some trees are highly 

 favored b^' all stages, others are less favored; some are attacked only when more 

 desirable food is not available, and some are never attacked. The young cater- 

 pillars of the first two stages cannot feed on coniferous trees, with the exception 

 of larch and blue spruce, but must have access to broad-leaved deciduous trees. 

 The older caterpillars, however, may attack and defoliate pine, hemlock, and 

 other coniferous evergreens. Usually only one complete defoliation is necessary 

 to cause the death of a coniferous evergreen; whereas most thrifty deciduous 

 hardwoods require more than one complete defoliation to cause death. Three 

 complete annual defoliations are sufficient to kill man\- hardwoods. 



