72 ENTOMOLOGICAL SOCIETY 



published by Doctor Howard.* At this trial, the machine did 

 not work satisfactorily. Only a few insects were trapped. 

 The most serious drawback is that a larger or smaller quantity 

 of fine dust goes along with each specimen that falls through 

 the funnel. This makes it much more difficult to pick out the 

 specimens than it would be to collect them in the first place 

 by the old-fashioned way. 



Mr. H. L. Frost, of the Cambridge Entomological So- 

 ciety, was invited to speak, and referred to what he considered 

 an interesting change of habit in the gipsy moth (Porthetria 

 dispar L.), discovered in the course of the campaign against 

 that pest. During the earlier years that the species was ob- 

 served, most of the larvae were on the lower limbs of the trees 

 and often crawled down the trunk, where they could be taken 

 by banding. Now most of them keep in the upper branches 

 and do not come to the bands. This makes the species more 

 difficult to combat. 



Doctor Howard said that in his opinion this was not a 

 change in habit, but a case of the survival of the fittest. The 

 individuals that had the habit of living on the lower limbs and 

 crawling to the bands were exterminated, while those that 

 remained in the tops were left to increase and perpetuate the 

 race. Mr. Schwarz disagreed with this. He thought that it 

 might be a true change in habit, caused by the difference of 

 the summer climate in America. The much greater heat may 

 cause the larvae to seek the upper branches, where it is cooler. 



Quite a discussion on the change of habit in insects followed. 

 Mr. Marlatt said he believed that certain races of a species 

 would acquire new food habits, or in other words that special 

 food-plant races of a species often develop. As examples of 

 this, he cited the following cases : The scale-insect Diaspis 

 pentagona Targ. has developed an American race that is in- 

 different to the mulberry, which is severely injured by that 

 species in Asia and Italy. Aspidiotus diffinis Newst. developed 

 a race on the U. S. Department of Agriculture grounds which 

 confined itself to a single variety of lilac, not even extending 

 to other varieties in close proximity. This habit was main- 



a Entomological News, xvn, No. 2, pp. 49-53, February, 1906. 



