246 MAINE AGRICULTURAL EXPERIMENT STATION. I907. 



hopes of finding them before the spring migration. During 

 June and July, 1907, (until N. solanifolii appeared upon the 

 potato) the search was continued until it seemed as though 

 every species of vegetation within aphid flight of potato fields 

 had been examined, but no N. solanifolii were chanced upon. 



Two conditions noted July 18, 1907, were of considerable 

 consolation in this connection. The first specimens observed 

 on the potato at the date were very few — one to about 3 rods — 

 a circumstance that might seem to indicate that the species was 

 not numerous enough upon anything to make a wholesale 

 migration necessary. A more puzzling fact was that the first 

 forms seen were wingless and solitary except for their own 

 progeny, and many of them had not yet begun to produce. 

 There was in this no basis for suspecting that any migration 

 in the usual sense, that is of a horde of winged forms, had 

 taken place, but rather that restless individuals had crept over 

 on to the potatoes from neighboring vegetation. Xo conclu- 

 sive statement, of course, would be justifiable upon observations 

 sc limited, and these suggestions relative to the manner of 

 migration are merely tentative. Insectary observations showed 

 this species to be active and restless at times both in the winged 

 and young apterous forms. 



The Practicability of Combating N. Solanifolii Upon 



Its Winter Host. 



Since for several consecutive seasons of excessive infestation 

 of the potato, N. solanifolii has while upon its winter (and 

 consequently late fall and early spring) host lived in such 

 restricted numbers that it was, to say the least, nowhere con- 

 spicuous, it is evident that any measure directed against this 

 species while upon its winter host is for Maine quite futile. 

 The readiness with which the insectary material accepted pea 

 vines and shepherd's purse lays this species open to the sus- 

 picion of not being confined to 2 hosts for Maine. Further 

 tests as to the wider range of food plants would be of much 

 interest and there is a possibility that a complete food list would 

 contain some helpful suggestions. Insectary tests as to a wide 

 range of food plants are contemplated as a part of the further 

 study of this species. As an example of the possible signifi- 

 cance of fuller host plant data may be cited the following 



