110 



nearly a tenth of an inch in lengfth and of a shining- brownish-black 

 color, with yellowish bands upon the leg-s. It is short and broad for 

 a plant-louse, and ver}^ broadly rounded behind. The winged louse 

 is of the same shining black color but is more slender than the 

 form just described, with the abdomen less rounded at the tip. 

 Several generations succeed each other during the season, the 

 young being brought forth alive. 



If this aphis should make its appearance in the nursery no 

 peach stock should be sent out without careful fumigation, unless 

 it should chance to be more convenient to dip the roots in kerosene 

 emulsion diluted to contain about 5 per cent, of kerosene. Of 

 course ground from which peach-trees infested by the aphis have 

 been dug should not be set to peaches again, but should be used 

 for some other stock. As the insect is not known to attack injuri- 

 ously any other kind of tree, although it has been found on the 

 plum, the resulting inconvenience will be slight. 



The Ckowx-gall. 



This is a dark, rough, abruptly protruding tumor (Fig. 1, i. 2 ; 

 Fig. 4), growing most commonly from the crown of the tree, and 

 varying in size from that of a pea to that of the fist, or larger- 

 the latter usually on old and long-infested trees. A badly affected 

 tree is likely to show signs of starvation, its growth ceasing and 

 its foliage having a sickly yellow look. Young trees often perish 

 from this disease, which is certainly contagious in some forms 

 and perhaps in all, and even large orchard trees may die and 

 finally break off at the base of the trunk. 



Although much the most common about the crown, just below 

 the surface of the ground, this gall frequently grows on the larger 

 roots, and is sometimes seen exposed upon the trunk. Appearing at 

 first as a simple small lump or tubercle, it may so extend its growth 

 as to girdle the trunk with its large wart-like excresences. Young 

 galls while still fresh have at first the color of the root from which 

 they grow, but later darken from the accumulation of dead bark 

 on their surfaces. They are at first, while very small, softer than 

 the healthy tissue of the root, but harden with age, and their inner 

 structure becomes irregular and confused. On old galls, soft, 

 white, growing points appear here and there in early spring, 

 which, enlarging rapidly, become gradually darker and harder, and 

 by fall take on the general apearance of the older growth. 



There is much evidence that the crown-gall of the peach, apri- 

 cot, and almond is a contagious disease due to a minute parasitic 



