102 



the trunk or branches. On the exposed parts of the tree 

 they are most likely to be noticed about the collar and at 

 the forks of the principal branches, or wherever an in- 

 jury to the bark has left a scar. When trees in a nur- 

 sery or young orchard have a sickly look — the leaves 

 dull and yellowish — and are not gTowing well, the pres- 



Fig. 7. — Woolly Aphis {Schizoneura laniger.) — a, Agamic fe- 

 male; b, larval house; c, pupa; d, winged female with antenna en- 

 larged above, all greatly enlarged and with wnxy excretin removed. 

 (Marlatt, U. S. Dept. Agr.) 



ence of this insect on their roots may be suspected even 

 though there may be no appearance of it on the bark 

 above ground. If the roots of such an infested tree be 

 examined they will commonly be found distorted and de- 

 formed with hard knot-like enlargements, many of them 

 almost dead, or even in course of decomposition. 

 These gall-like growths occur on roots of all 

 sizes to a depth of a foot or more beneath the surface. 

 Unless the tree is so far gone that the insects have de- 

 serted it, they will commonly be found upon these in- 

 jured roots at all seasons of the year. 



The apple is the only tree liable to attack by this in- 

 sect, the current supposition that it may live on the 

 roots of forest trees being an error due to confusion of 

 injury by the woolly aphis with that by the root-rot. As 



