ABSTRACTS. 355 



Mass., on August 17, which she shared with the writer. At 

 this date the galls contained only unknown nymphs of a Psyllid 

 but they were about ready to wing and the adults began to 

 emerge in large numbers on August 20-21. These proved to 

 be Livia maculipennis Fitch. 



. 



CONCERNING PROBLEMS IN APHID ECOLOGY.* 



It is apparent enough that in ecological work with an aphid, 

 the fact of first importance to be ascertained is whether a given 

 species is migratory, for, if it have two types of host plants, 

 the problems that concern its life cycle are doubled, though 

 the economic situation may be simplified by virtue of a greater 

 choice in methods of control. 



Why should it not be a simple matter — the mere finding 

 out whether a species is migratory? Partly because every 

 aphid cycle we learn is as likely to mislead as to guide us with 

 the next species we investigate. We are in the habit of saying, 

 for instance, that we know that Aphis pomi, Myzus cerasi, and 

 Schizoneura rileyi do not migrate because they occur at all 

 times of the year upon a single food plant, respectively the apple, 

 the cherry, and the elm. That in itself is no reason for surety, 

 for Prociphilus tessellata, P. venafuscus, and Schizoneura 

 lanigera each occurs at all times of the year upon a single food 

 plant, respectively the alder, the balsam fir, and the apple, and 

 yet these are all migratory aphids. There is this distinction 

 between these two cases, however, the three species first men- 

 tioned occur at all times of the year upon their primary food 

 plant and the second three do not — with them it is their sec- 

 ondary food plant which harbors them for twelve months of 

 the year in addition to their winter and spring residence upon 

 their primary host. By "primary host" is understood that plant 

 upon which the over-wintering egg is normally deposited and 

 upon which the stem mother and her immediate progeny 

 develop. The "secondary host" is that plant to which the spring 

 migrants fly and from which they return to the primary host. 

 At present I know of no member of the subfamily Aphidince 

 which resides for twelve months upon its primary host and in 



*This is an abstract of a paper with the same title, by Edith M. Patch, 

 published in Journal of Economic Entomology, Vol. 9, pp. 44-51. 



