Rep07is to various Correspondents. 91 



The apparent connection between tlie two is of some economic 

 importance if, as seems essential, larch can only be infected from 

 spruce. Should this actually be so, and I see no reason to doubt it, 

 then it would l)e as well to give up mixed spruce and larch plan- 

 tations, the two trees being grown apart and separated by intervening 

 non-coniferous plantations. 



The Spruce Gall Aphis occurs in N. America. It is said to have 

 been introduced with N. European and Norway spruces. It was 

 described as Chermes abieticolens by Dr. Thomas in his Iteport for 

 Illinois for 1879, p. 150, but was proved by Cholodkowski to be 

 C. ahietis. It is common in Continental Europe, occurring as far 

 south as Parma. 



Treatment. 



With regard to treatment, all we can do is to wash the affected 

 trees with paraffin emulsion for larch attack whenever we see the 

 pest present, and for spruce when we observe the winged forms 

 issuing from the galls, and in the spring just before the galls are 

 beginning to form. Small trees should Ije gone over before the galls 

 open and all such growths picked off and destroyed. These galls 

 stunt and deform the trees when young, and should certainly be 

 collected if we wish the plantation to develop into a good growth. 



Natural Enemies. 



Various Lady-birds feed upon the Spruce Gall Aphis (Scymnus, 

 Coccinella) and also the larvje of Lace Wing Flies (Chri/sopa). 

 Numerous Spiders also feed upon them. 



The Ash and Willow Scale. 



(Chionaspis saiicis, Linnaeus = Cffuxini, Signoret.) 



Frequent enquiries have been received lately concerning a scale 

 on ash saplings. This scale is certainly very harmful to the 

 saplings, but in no case can I find that they have caused the death 

 of tliem. Some under observation close to my own house were 

 literally covered with the scales, and yet kept alive. On the other 

 hand their growth was decidedly checked. Certain clean saplings 

 growing side by side with those smotliered in scale were an inch 

 more in diameter than the affected ones. 



This scale is said to inhabit the willow as well as the nsli, and 

 also to occur on alder, hawthorn, privet and lilac. To osiers it is 



