304 ANNUAL KEPOBT. 



and shrubs. In the 14th annual report of the Geologist and Natural History Survey 

 of Minnesota I give a list of all the species observed in this locality — some seventy 

 and odd species— to which I refer those v/ho may wish a more extended account. 



The species that probably more than any other concerns the horticulturist is the 

 apple-tree aphis (Aphis mali, Fitch.) It is found very common in Hennepin and 

 Ramsey counties, and most lilcely is already found over the whole State wherever 

 the apple is grown. A number of young trees lately set out on the experimental 

 farm of the University were observed to be badly effected. In this case the trees 

 very likely were infested by the aphis, or at least the eggs, before being set out, 

 or they would hardly have occurred in such great numbers as they did, there being 

 no orchard very near. It would therefore be well to have trees inspected before they 

 are set out in a new place where the aphis is not likely to be found before, and if 

 aphis or eggs be found, that they be well cleaned so as to make them exempt from 

 this pest, at least for a year or two, until they can be well rooted and better able to 

 withstand. A 3'^oung tree on being transplanted has all it can do under ordinary 

 circumstances to accommodate itself to the new locality without having in addition 

 hereto myriads of aphis continually pumping the sap and destroying more or less 

 of the leaves. After a tree has well come under growth it can withstand the 

 presence of aphis as ordinarily found without very much injury, except when 

 circumstances are more favorable for the aphis than the tree, as we some years find 

 to be the case, when even a healthy and well grown tree will become much injured 

 and even succumb. 



Together with the apple trees, the mountain ash was also found to be badly 

 affected by the same species of aphis. As far as I am aware, the apple tree aphis 

 has never been recorded as affecting the mountain ash, although we might expect 

 this to be the case from the close botonical relation of the two species. 



The species inhabiting the cherry, (Myzus cerasi, L.), although not observed in 

 this vicinity, is known to occur in the State. It is very similar to the apple aphis- 

 in habits, and often quite as injurious. 



A closely related species is the one found on the currant, (Myzus ribus L.), 

 observed to be rather common in this county, and to cause a good deal of injury 

 by cupping the leaves, or forming hollows on the under side with corresponding 

 chiefly swellings on the upper side. Jjcaves so affected turn yellow and fall off 

 before the usual time. 



Several of the more favored shade trees are more or less affected by species of 

 aphis. This is particularly the case with the white elm that is affected by two 

 rather common species. One of these, (Schizonera american, Keily), gnarling and 

 curling the leaves, making them unsightly and of no use to the tree, and the other 

 species, (OlypMna compressa, Koch), forming the cock's-comb galls so often seen 

 on the leaves. Young trees, especially, are often found to be badly affected, and 

 much injured by the combined efforts of the two species. 



The boxelder, that is often met with in this county, and seems to be much fav- 

 ored as a shade- tree on account of its rapid growth and fine appearance is also often 

 found badly affected by a \ea,f.\jiha,hitiTig speciea {ChaitophorusnegundiTiis,Th.os.), 

 and made unsightly by the filthy appearance of the foliage when badly affected. 

 As before stated, the eggs of this species were observed very plentiful last fall, and 



