October, '12] PATCH: WOOLLY APHID MIGRATION 395 



of this kind it should be remembered that the number of eggs hatched 

 is of much greater importance than the number failing to hatch. 

 With these results, then, it is evident that lime-sulphur, even too strong 

 for use on foliage and fruit is, at best,, an uncertain ovicide, its effective- 

 ness of doubtful value economically. 



WOOLLY APHID MIGRATION FROM ELM TO MOUNTAIN 



ASH^ 



Schizoneura lanigera (americana) 

 By Edith M. Patch 



In the vicinity of Orono, the woolly aphid of the apple, Schizoneura 

 lanigera, was abundant during the late summer and autumn of 1911 

 upon water shoots of certain apple trees; and upon trunk and branches 

 of native mountain ash, Pyrus (Sorbus) americana; cultivated orna- 

 mental species of mountain ash, Pyrus sitchensis and others; and 

 native and cultivated species of hawthorn, Cratcegus. Some of 

 each of these trees were located with the view of studying the over- 

 wintering forms of this aphid, -some of which, according to all pub- 

 lished accounts, migrate up from the base of the tree in the spring to 

 tender and susceptible places on the bark where they establish bark 

 feeding colonies. No such occurrence, however, took place here the 

 spring of 1912. The identical trees which were heavily infested with 

 woolly aphid last fall were free from infestation this spring until late 

 in June and then the infestation did not come from root aphids. 

 Whether lanigera ever overwinters on the apple in this climate one 

 season's observations are of course insufficient to ascertain. I had 

 heretofore taken it for granted that it would do so and this point has 

 not been previously investigated in this locality. Testimony as to 

 this habit is desirable from other northern states and I shall plan to 

 continue observations here for some years to come. It should be 

 stated that these notes concern the trunk, branches and water shoots 

 only; no roots being examined. If, however, root forms were pres- 

 ent they and their progeny certainly remained buried this spring, as 

 daily observations of selected trees were made. It seems not improb- 

 able that the hard packed condition of the clay soil in this immediate 

 vicinity may be partly responsible for this circumstance. The fall 

 migrants of this colony were mature and taking flight September 

 20-23. 



1 Papers from the Maine Agricultural Experiment Station: Entomology Xo. 59. 



