334 REPORT OF STATE BOARD OF HORTICULTURE. 



of hard fibrous enlargements, with the result in a year or two of the dying 

 of the rootlets and their ultimate decomposition with attendant disappear- 

 ance of the galls and also of the lice, so that after this stage is reached, the 

 cause of the injury is often obscure. On the trunks the presence of the lice 

 sometimes results in the roughening of the bark or a granulated condition 

 which is particularly noticeable about the collar and at the forks of branches 

 or on the fresh growth around the scars caused by pruning, which latter is 

 a favorite location. On the water shoots they collect particularly in the 

 axils of the leaves, often eventually causing them to fall, and on the tender 

 greener side of the stems. The damage above ground, though commonly 

 insignificant, is useful as an indication of the probable existence of the lice 

 on the roots. A badly attacked tree assumes a sickly appearance and does 

 not make satisfactory growth and the leaves become dull and yellowish, and 

 even if not killed outright it is so weakened that it becomes especially 

 subject to the attacks of borers and other insect enemies. Injuries from the 

 woolly aphis are almost altogether confined to the apple, even the wild crab 

 not being so liable to attack or at least injury by it. There is, however, 

 some difference exhibited by dift'erent varieties of apple in immunity, and 

 particularly is the Northern Spy proof against it, and it is possible that, as in 

 the case of the grape phylloxera, by employing root stock from seedlings of 

 the more resistant varieties, or from wild crabs, considerable protection would 

 result. The character of the soil also exerts some influence, that is, loose 

 dry soils are favorable and wet compact ones are unfavorable to the aphis. 



ORIGIN AND DISTRIBUTION. 



There is considerable difference of opinion as to the origin of the woolly 

 louse of the apple. The belief has fluctuated between a Europea and an 

 American origin for this insect, but the weight of evidence seems to indicate 

 the latter. At any rate, it is an insect which is most readily carried from 

 place to place with nursery stock of the apple, and it has boen so transported 

 to practically all the important countries of the world which have been 

 reached by colonization or European settlement. The woolly apjiis was first 

 noticed in England in 1787, on some stock imported that year from America, 

 and was early called the American blight. Hausmann described it in 1801 

 as infesting apple trees in Germany, and within the next twenty-five years 

 it was recognized as a serious enemy of this fruit tree throughout England, 

 Belgium, North France, and Germany, but seems never to have been 

 especially notable in the warmer latitudes of Europe. 



It was very early introduced into Australia and New Zealand, and is 

 known in India and Chile, and probably is as widespread as any of the com- 

 mon injurious fruit pests. Notwithstanding the possibility of its being a 

 native American insect, it did not attract attention in this country much 

 before 1850. Its spread since has, however, been rapid, and it now occurs 

 practically wherever the apple is grown. It has been reported to this 

 division from no less than thirty-five states and territories and nearly one 

 hundred localities. It is particularly abundant and injurious in the latitude 

 of the Ohio Valley. While seemingly, therefore, somewhat aft'ected by 



