334 MAINE AGRICULTURAL EXPERIMENT STATION. I916. 



proved too much for the little seedling which was so nearly dead hy 

 August 10 that the last of the aphids perished at that time. 



Schizoneura americana is a name which until recently has been com- 

 monly applied to two distinct species by American entomologists. 



One of these species inhabits the leaf cluster or aphid rosette of 

 the American Elm (Figs. 59 and 60). This migrates to apple, several 

 varieties of mountain ash (Pyrus sp.) and to hawthorn {Crataegus), 

 where it was familiar as lanigera long before its identity with the 

 aphid of the elm rosette was suspected. The life cycle of this species 

 so far as personally ascertained by the writer is recorded in the present 

 paper. This species is found in Maine, Missouri, Colorado* and 

 doubtless all the way between. Like other aphids it is fluctuating in 

 its abundance, being conspicuous some years and comparatively rare 

 during other seasons. 



*That Messrs. Gillette and Bragg were mistaken in their opinion that 

 the rosette aphid in Colorado did not migrate to the apple in accord- 

 ance with its habit in Maine {Journal Economic Entomology, Vol. 8, 

 p. 100) is shown by the observations of Mr. Maxson (Entomological 

 News, Vol. 26, pp. 367-368). Although Professor Gillette has not yet 

 published his later observations, so far as we know ; that they agree with 

 those of Mr. Maxson is indicated in a letter from him to the writer 

 under date of June 25, 1915, from which the following paragraphs are 

 quoted : 



"You will be interested to know that the rosette form of the elm 

 Schizoneuran is very common about Fort Collins this year, and the 

 winged forms are now leaving the leaf clusters in great numbers, and 

 for the first time since we began the study of this insect, we find the 

 lice locating in considerable numbers upon the under side of the 

 leaves of apple trees. 



"In many instances we are able to find the young that they are depos- 

 iting, and in many instances, also, it seems probable that a colony of 

 young lice in the axils of the leaves are the product of these winged 

 lice from the elm. So it begins to look as though we shall have to 

 admit that there is a natural migration of this elm Schizoneuran to our 

 apple trees. 



"We had been able, repeatedly, to get these lice to take in small num- 

 bers in our breeding-cages, and I find that last year Mr. Maxon of 

 Longmont had found this louse going to the apple in the field, but until 

 a few weeks ago, he had not communicated the fact to me. It really 

 looks now as though our observations here would fully confirm your 

 observations in Maine." 



The experiments of Mr. Baker proved that in the localities in which 

 he worked the elm is the winter host of lanigera (Report No. 101, U. S. 

 Department of Agriculture, Office of the Secretary. 1915). The life 

 cycle of this aphid, therefore,, as discovered for Maine by the writer, 

 does not seem to be exceptional for America. 



