1 14 FORESTRY IN NEW ENGLAND 



leaf. The full-grown caterpillar is about one-half inch long with 

 a broad, yellowish stripe down the center and a narrower strip 

 of the same color on each side. The pupa is a bright orange 

 yellow about one-fifth of an inch long. 



Life History. — The transformations of this insect follow each 

 other so rapidly that unless one knows just what to look for he 

 is apt in combating the pest to do the wrong thing at the wrong 

 time. The beetles pass the winter in sheds, attics, and in other 

 sheltered places and emerge in the first warm spring weather. 

 Late in April or with the appearance of elm leaves the beetles 

 fly into the trees and begin defoliating. Before the latter part 

 of June when the eggs are all laid, much damage may be done. 

 Early in June the young grubs hatch out and begin to eat the 

 leaves. They complete this stage in about three weeks and then 

 pupate, developing into the beetle in a few days. As there are 

 usually two broods in a season the foliage may be destroyed, re- 

 newed, and again destroyed, which is very weakening to the tree. 



Treatment. — Many of these insects are killed by a fungus 

 and by parasites. The success of any treatment depends on 

 accurate observations. Much can be accomplished by spray- 

 ing the underside of the leaves in early spring with arsenical 

 poisons when the grubs begin to feed. There should be no de- 

 lay in this work. When the caterpillars crawl down the trunk, 

 large numbers of them may be killed by spraying with kerosene 

 emulsion, soap solution, or by pouring boiling water on them. 

 Banding the trees is of no use in combating the insect, since it 

 works down the tree instead of up. The successful methods of 

 fighting the elm-leaf beetle cannot be used in forestry work on 

 account of the expense. 



Forest Tent Caterpillar,^ or Maple Worm (Malacosoma 

 dis stria). 



Form of Damage. — A few years ago this insect caused a great 

 deal of damage throughout the northeast by defoliating sugar- 



1 See New York State Museum Memoir 8, " Insects Affecting Park and Wood- 

 land Trees." 



