■ 418 



M. solanifoUi, and then on wild rose. There seems no reason to ques- 

 tion the conchision that the ragwort material, first taken in July, had 

 had its origin in migrants from the rose. Stragglers of both species 

 remained on the rose during the summer. Experiments showed 

 M. pseudorosae to be able to live and produce young on ragwort, and 

 the young matured on the secondary food- plant. It is possible that 

 it may prove to be synonymous with M. rosaeformis, Das, from India. 



M. solanifoUi, on migrating from the rose, commonly causes heavy 

 infestation of the potato, and perhaps transmits the mosaic disease of 

 that plant. M. rosae is not known to migrate. 



A key to the New England species of Macrosiphum is given, and 

 the following new species described : Macrosiphum carjnnicolens, 

 on blue beech {Carpinvs cawliniana) ; M. ptericole7is from fronds of * 

 bracken {Pteris aqiiilina) and lady fern {Atliyrium jilix-foemina) ; 

 M. diervillae from wild bush honey-suckle {Diervilla lonicera) ; 

 M. impatiensicolens from stem of terminal shoots of Impatiens biflora ; 

 M. amelanchiericolens from Amelanchier spicata ; M. onagrae on evening 

 primrose {Oenothera biennis) ; M. pseudocoryli from ironwood {Ostrya 

 virginiana) and hazel bush {Corylus rostrata) ; 31. pseudodirhodum on 

 greenhouse and wild roses ; M. gravicornis on Solidago ; M. eupatori- 

 colens on Eupatorium purpureum ; and 31. lanceolatum on Solidago 

 lanceolata. 



This bulletin also contains a further instalment (Part VI) of the 

 author's food-plant catalogue of the Aphids of the world. \Cf. R.A.E., 

 A, vii, 243.] 



Patch (E. M.). The Life-Cycle of Aphids and Coccids. — Ann. Entom. 

 Soc. America, Columbus, Ohio, xiii, no. 2, Jmie 1920, pp. 156-167. 



This paper, forming part of a Symposium on " The Life Cycle in 

 Insects," discusses the difficult problems of the life-cycles of Aphids, 

 which, although governed by certain rules, are very confusing owing to 

 the unusual phenomena that occur in the course of the life-history of 

 any species. The overwintering egg is true to the rules governing 

 Hexapods, but between each sequence of such eggs there is a succession 

 of remarkable phenomena, including parthenogenetic viviparous 

 generations, extreme examples of polymorphism, alternation of 

 generations in a series where a duplication may not occur for seven or 

 more generations, parallel series in which certain females give birth 

 to true sexes, while others of the same generation give rise to normal 

 young that hibernate in the first instar without feeding, and a system 

 of seasonal migration that is unsurpassed by any in the animal kuigdom. 

 All these divergences from the normal may be exhibited in a single 

 species. Typical life-cycles of Eriosoma lanigerum, Horn\aphis 

 hamamelidis, Chermes and Phylloxera are given in illustration. The 

 relations of the Aphid to its environment and the manner in which it 

 controls and selects that environment are discussed. The instinct 

 that prompts the autunm migration is not understood, but whatever 

 the cause, it is always once and once only in seven generations that the 

 autumn migration takes place from secondary to primary host and the 

 reverse migration in spring. It is obvious that environment is influen- 

 tial in the production of winged forms, and that migration is correlated 

 with exhaustion of the infested food-plant in the spring and with 



