572 STATE BOARD OF AGRICULTURE. 



THE BLACK PEACH-APHIS. 



[Aphis persicce-niger Smith. ) 



Next to the San Jose' scale, the worst enemy to the peach in our State 

 is the black peach-aphis (Aphis persicce-niger). This dangerous pest was 

 first recognized in Michigan during the year 1889 by Dr. Erwin F. Smith.* 

 Like the wooly aphis of the apple, this louse does not confine its opera- 

 tions to the branches and trunk of the tree, but works on the roots as 

 well. It may be found on almost any part of the roots, but seems to 

 prefer the smaller rootlets, on which it gathers in great numbers. Its 

 work on the branches and leaves, while of a very serious nature, is not 

 so dangerous to the tree as that on the roots. Ordinarily the lice may 

 be found on both leaves and roots at the same time, but they may con- 

 fine themselves temporarily to either one, the proportion underground 

 varying at different seasons and according to the character of the soil. 

 Sandy soil seems to be favorable to the root-form, while stiff clay is less 

 liable to harbor them, although they may become troublesome even in the 

 stiffest clay soil. 



The insect itself is a small black louse, either winged or wingless. 

 The winged form is about one twelfth of an inch in length and measures 

 a little more than one-quarter of an inch across the wings from tip to tip. 

 The wingless form is somewhat smaller. In color the insects are shiny 

 black except on the under side, which is dark, shiny brown. 



While this shiny black louse is easily distinguished from other lice 

 infesting the peach, it is well with the aid of a microscope to examine 

 the roots, when its presence is suspected, and if found there to send a 

 quantity of specimens in a tight tin box to the consulting entomologist 

 for accurate identification. 



The effect of root-lice is apparent in the sickly appearance of the trees 

 (Fig. 5). Their most serious depredations are committed on young trees, 

 whose stunted or dwarfed and starved appearance first attracts atten- 

 tion. The leaves turn yellowish, usually become somewhat curled, and 

 it is said that the general appearance is suggestive of the first stage of 

 yellows. Of course the only real proof lies in finding the insect, either 

 on the leaves or on the roots. 



REMEDIES. 



Unfortunately, as these lice live both on the leaves and on the roots, 

 the work of extermination requires concerted action against them in both 

 of these places. The leaf or aerial lice are easily disposed of by a spray 

 of kerosene-emulsion (Hubbard formula), using one part of the emulsion 

 to ten of water; or by a spray of whale-oil soap at the rate of one pound 

 of soap to six gallons of water; or strong tobacco-water may be used 

 in the form of a spray. The root-inhabiting form, however, requires a 

 more laborious and expensive treatment. Probably the best remedy for 

 root-lice is tobacco-dust. It must be dust and not merely waste or 

 chopped tobacco, for experiments have proved that coarse tobacco is 



*Ent. Amer. 1890, pp. 101 and 201 



