February, '17] ENTOMOLOGISTS' DISCUSSIONS 93 



spent in trying to dispose of the infestation in the lodgepole to protect 

 the yellow pine would be wasted. Whether or not other species of 

 economic insects respond in a like manner to the influence of one or 

 more of their multiple host species, I do not know, but it is probably 

 true with many and the determination of the facts will lead to a more 

 economic method of dealing with them. 



Mr. T. J. Headlee: This address has drawn attention to a very 

 interesting and important phase of our work. The feeling that the 

 pioneer life-history work on our insects of large economic importance 

 is approaching completion and that we should now look a little deeper 

 has been growing. I heard from Doctor Shelford yesterday that the 

 University of Illinois is erecting a large vivarium in which is to be in- 

 stalled apparatus for the conditioning of environmental factors in such 

 a fashion that the effect of particular factors can be accurately 

 measured. If this may be taken to indicate that the universities of 

 the country have realized the value of determining the laws which 

 govern the response of living matter to environmental factors and 

 have set out to furnish facilities for collecting data, we have reason 

 to hope that important discoveries bearing upon the phases of re- 

 search mentioned by our President will not be long delayed. It 

 seems to me that this address should be taken by our research member- 

 ship to mean that the time has arrived when we must give more at- 

 tention to the stimuli that influence life-history activities 



Mr. W. M. Wheeler : I might mention one case that recently came 

 to my notice that has an interesting bearing on Doctor Hewitt's address 

 and also on Doctor Hopkins' remarks. I had two students working 

 to get a medium on which they could raise banana flies, Drosophila, 

 and Doctor Glaser made a medium of banana agar and another medium 

 with agar of potato and found that flies would oviposit on the banana 

 agar. They were evidently attracted to the banana by a chemotropic 

 reaction to the banana. Now if the flies were brought up on banana 

 agar, they will also oviposit on potato agar but the larvae will not 

 develop readily on potato agar. There is something like memory in 

 this matter and is somewhat similar to Doctor Hopkins' Dendrodonus 

 monticokc. 



Mr. a. D. Hopkins: Mr. Craighead is carrying on many experi- 

 ments at our field station at East Falls Church, Va., to determine the 

 extent to which insect species are influenced by their host species. He 

 has found that while Callidium antennatum infests a number of host 

 species, representing different genera such as Juniperus, Pinus, Picea, 

 etc., individuals breeding in one host can not be forced to even oviposit 

 on another. He has even transferred the larvae from one host to an- 

 other but without success, while such a transfer in the same host is 

 successful. 



