February, '15] 



GILLETTE: APHID FOOD PLANTS 



99 



Thecahhis popiiliconduplifoliiis Cowen 



This species has Populus occidentalis for its over-winter and early- 

 summer host, and migrates to native species of Ranunculus for the 

 later summer and fall months. Transfers between these host plants 

 are readily made artificially and the lice do not all leave the Ranun- 

 culus in the fall, so that they may be found upon Ranunculus the year 

 round. In fact, many lice having alternate host plants infest one 

 of the food plants continuously, a portion of some brood acquiring 

 wings and migrating to a different species of plant as an alternate host. 

 Prociphilus corrugatans Sirrine 



Occurs commonty upon Cratcegus species as a winter host; alternate 

 host unknown. 



Prociphilus alnifolice Williams 



Occurs upon Amelanchier alnifolia as the over-winter host; the al- 

 ternate host unknown. 

 Colopha ulmicola Fitch. 



Occurs upon Ulmus americana as the winter host, and upon Era- 

 grostis species during later summer and fall. The migrants returning 

 during September and October to the elms. 

 Tetraneura graminis Monell 



Occurring upon Ulmus americana as the winter host, and upon rice 

 cut-grass, Persia oryzoides, during the summer and fall. 

 Schizoneura americana Riley 



The sexuparse of this species fly in great numbers to the trunks and 

 lower limbs of the American elms during the months of September 

 and October each year. The sexual males and females are deposited in 

 any hiding place beneath bits of bark where it will be difficult or im- 

 possible for Coccinellids to reach them. The eggs laid by these sexual 

 females hatch into stem-mothers the following spring that locate upon 

 the young opening leaves and start the generations that cause the 

 leaf-curl gall that Riley figured as the gall of americana. The spring 

 migrants resemble the return migrants of the fall, and neither should 

 be confused with the fall migrants from the apple (lanigera) which are 

 bark feeders and which differ markedly from americana in both anten- 

 nal and wing characters. So, while it seems certain that this species 

 has an alternate food plant upon which it lives during the latter part 

 of the summer, we have not been able to locate it. 

 Schizoneura rileyi Thomas 



This species, also occurring on the elm, but always as a bark feeder 

 like lanigera of the apple, deserves mention for the purpose of avoid- 

 ing confusion with the other elm species. It is quite distinct from the 

 other species of the genus mentioned and probably has no alternate 



