726 JOURNAL OF HIE ROYAL HORTICULTURAL SOCIETY. 



the ridges, and by the borders of streams and lakes. Nearly every farmer 

 owns a woodlot. which he turns to practical use in the construction of 

 fences and for firewood, any remaining lots being disposed of in the 

 market, for which, evidently, both demand and prices are good. The 

 c hapter on pruning and how far it should be carried out is decidedly 

 practical ; while the notes on insect pests and damage by fire and wind to 

 the forests show lucidly what has to be contended with in the rearing and 

 converting of timber in Southern New England. The excellent illustra- 

 tions go far in elucidating the text. — .4. D. W. 



Woolly Aphis of the Apple (Schizoneura lanigera Hausmann). 

 By C. L. Marlatt {U.S.A. Dept. Ayr. Div. Ent., Circ. 20 (2nd series), 

 illustrated). — The woolly aphis manifests itself in two forms, above 

 ground and on the roots, the latter frequently damaging young trees and 

 nursery stock. Like the phylloxera on Vines, it produces swellings and 

 galls on the roots and poisons the tissues, besides exhausting the vital 

 juices of the plant. When the tree has become established it is less 

 dangerous. The aerial form is useful as indicating the probable presence 

 of the aphis on the roots, which, when it does not kill the tree outright, 

 weakens it and exposes it to the attacks of insect enemies. Some varieties 

 of Apple, and also the Crab, do not suffer from this pest, and probably 

 the use of such stocks would procure immunity. Its origin is probably 

 American ; it was first noticed in England in 1787 on stock imported 

 from America, where it spread rapidly. It is more noticeable in the 

 northern than in the southern latitudes of Europe. 



Its life-history is complicated, and probably resembles that of the 

 phylloxera. The aerial form is killed out in winter by severe cold, but 

 the root form persists through the winter and gives rise to new generations 

 in the spring. Remedies are easily applied to the former, and consist 

 of the usual washes, but the root form is more difficult to reach. Water 

 at nearly the boiling point has been used successfully and does not injure 

 the roots of even young trees. Finely-ground tobacco dust is remedial 

 and protective. It only costs about one cent per pound, and is besides 

 worth its cost as a fertiliser. Bisulphide of carbon destroys the louse, 

 but does not protect against future attacks. It may be dangerous to the 

 tree if not carefully used, is highly inflammable, and more expensive than 

 the tobacco dust. 



Nursery stock can be sent out clean by pruning the roots when taken 

 up, and immersing for a few seconds in water at 120° F. Strong soap 

 solution and kerosene emulsion are still more certain remedies. 



Good cultivation in newly-planted orchards is absolutely essential for 

 the first two or three years, that being the danger period ; established 

 and strongly-growing trees are less susceptible to the attacks of the root 

 louse, while ill cult i \ ated, neglected orchards are sure to succumb. 



The natural enemies of the woolly aphis are generally sufficient to 

 protect mature trees from attack, the nine-spotted lady-bird's larva? being 

 particularly useful. — C. H. C. 



Yucca karisruhensis | Y. filamentosa x Y. glauca). By L. 

 (iraebener {Die dart. p. 7. October 8, 1903).— In Germany, where the 



