42 Experiment Station Bulletin 363 



There was an outbreak of canker worms in localized areas of the 

 state, causing heavy defoliation of elms, particularly in the Merrimack 

 \'alley. 



The black army cutworm which caused such destruction in the blue- 

 berr\' sections of Maine occurred only in one small area in southeastern 

 New Hampshire and caused no serious damage. 



J. G. Con KLIN 



Apple Maggot 



In the summer of 1944, DDT was used in the control of the apple 

 maggot at the Horticultural Farm. Three plots were used in the experi- 

 ment. In plot No. 1 DDT in the form of Gesarol AK 20, at two pounds 

 per 100 gallons of water, was applied twice for the control of apple mag- 

 got. In plot No. 2, DDT was used only in one application, and in plot 

 No. 3, the standard lead arsenate program was carried out, for compari- 

 son. In the control of the apple maggot Gesarol AK 20 spray was only 

 slightly superior to lead arsenate. The omission of one cover spray in 

 plot No. 2 resulted in somewhat poorer control. On the basis of the 

 work carried out in 1944 it would appear that increased dosages might 

 prove to be of practical value in the control of apple maggot in New 

 Hampshire. However, it is expected that DDT in the form of dusts may 

 give better results in the control of the apple maggot. It was planned 

 to carry out such a test as opportunity presents itself during the coming 

 season. 



In the course of the above experiment it was found that DDT gave 

 verv poor results against the plum curculio, but gave satisfactory results 



against apple aphid. 



J. G. CoNKLiN. W. C. O'Kane 



Studies on the Ecology of European Spruce Sawfly 



The European spruce sawfly continues to maintain itself at a low 

 population level in southern New Hampshire, also in the extreme north- 

 ern part of the state. In stands of spruce visited during 1944 the spruce 

 sawfly could be located readily, but in no instance was defoliation no- 

 ticeable. 



Cocoons of the sawfly collected and brought to the laboratory 

 yielded some of the parasite, Microplectroii. which had been liberated 

 during the year when the spruce sawfly first became a serious pest. It is 

 interesting to note that the parasite is apparently able to maintain itself 

 even when the spruce sawfly is at a very low population level. 



Some scouting for the spruce budworm \\2.s carried on during the 

 season of 1944, and again during the earlv part of June, in 1945. In 1945, 

 the spruce budworm was found at several points in the towns of Clarks- 

 ville, Pittsburgh, and Colebrook. Fortunately, no evidence of spruce 

 budworm defoliation was found. Timberland owners have been informed 

 of the possibility of an outbreak occurring some time in the relatively 

 near future, and thev have been advised to contact the department im- 



