OF WASHINGTON. 11 



Doctor Hopkins's observations indicated that one or two 

 complete defoliations of coniferous trees usually resulted in 

 their death, excepting the larch, which succumbs after the 

 second or third defoliation. 



Records of depredations by the " Nonne " moth (Liparis 

 wonacha L.) in the coniferous forests of Europe indicate that 

 a vast amount of timber has died at different times during the 

 past four hundred years as the result of defoliation and sub- 

 sequent attacks by barkbeetles. Doctor Hopkins stated that 

 his observations in this country indicate that coniferous trees 

 defoliated by insects or injured by diseases of the foliage 

 are not as attractive to barkbeetles and bark-boring insects 

 as are those injured by lightning, deadened, or felled with 

 the axe, or broken by storm. 



Mr. Burgess said that defoliation in the fall often causes 

 serious injury to nursery stock and larger fruit trees, for it 

 causes the buds to start and thus results in winter killing. 

 Mr. Hunter thought that the climatic conditions which follow 

 the defoliation might have a great deal to do with its effects. 

 Mr. Piper questioned the statement that defoliation is always 

 fatal to coniferous trees and said that many yellow pine trees 

 in eastern Washington and Idaho had recovered after com- 

 plete defoliation by the pine butterfly (Neophasia menapia 

 Feld.). Mr. Webb said he had observed this same condition 

 in Idaho. 



Mr. W. J. Phillips read the following paper: 



NOTES ON TOXOPTERA GRAMINUM AND PARTHENO- 

 GENESIS OF ONE OF ITS PARASITES. 



[Hemiptera-Homoptera.] 

 By W. J. PHILLIPS. 



Observations were made on the spring grain-aphis (To.vop- 

 tera graminum Rond.) at Richmond, Ind., from June, 1907, 

 to December n, 1907. During this period a number of inter- 

 esting things came to light. 



It was observed that Toxoptera molts but four times ; and, 

 even under the most favorable conditions, the period between 



