54 



Mr. Hopkins stated that there was a possibility of variation in a 

 species having something to do with its change in habit from an enemy 

 of secondary to one of primary importance. Referring again to the 

 species Dendroctonns frontalis, he had concluded, after a study of 

 many hundreds specimens, that it was a variety of this which was so 

 destructive to the pine forests in West Virginia, and that it had appar- 

 ently varied from the typical species in a way to enable it to become 

 more destructive. He thought that if it is possible for it to vary in 

 that direction it is also possible for it to vary in another direction, and 

 thus become more sensitive to climatic and other conditions which 

 would exterminate it, as it was exterminated b} T the severe cold of 1893. 



Mr. Felt called attention again to the forest tent caterpillar and stated 

 that in New York State at least the evidence was very largely in favor 

 of the insect being controlled by its natural enemies, for the simple 

 reason that, in looking over the infested areas, it is found that the 

 places where it is most abundant move gradually away from the locality 

 where the original outbreak occurred. These localities of severe infes- 

 tation have been moving eastward in New York State, and he could 

 readily see how parasites or natural enemies might become locally 

 abundant on account of the numbers of the caterpillars. 



Mr. Weed agreed with the opinion held by Mr. Felt, and mentioned 

 one or two localities in New Hampshire which supported this view. 

 He spoke of one region where the Dipterous enemies were very 

 abundant. 



Mr. Felt remarked that in regard to the tussock moth in Washing- 

 ton, he believed it to be held that this insect had been largely checked 

 by its parasites. 



Mr. Skinner stated that he recalled Mr. Howard's statement in ref- 

 erence to this point, and said that the same condition was true in Phila- 

 delphia. It had been his observation that parasites increased largely 

 during the abundance of their hosts. 



Mr. Osborn stated that from his point of view it was evident that 

 there was some general influence affecting the abundance of insects, 

 and that there must be some widespread condition also affecting para- 

 sites. The squash bug had been present in Ohio, but not so abundant 

 as last year. He had observed that a considerable number hibernated 

 during the past winter. The chinch bug hibernated last year in large 

 numbers and promised to do a great deal of damage the present sea- 

 son, but early summer rains came in such quantities that the insects 

 were destroyed. They practically disappeared in injurious numbers 

 after the first of July. The cankerworm had been very abundant in 

 Ohio, and the fall cankerworn had appeared in considerable numbers, 

 and he thought it likely that it would prove quite abundant in the 

 spring. 



Referring again to the forest tent caterpillar, Mr. Weed stated that 

 in New Hampshire, to which State his remarks referred, the facts 



