92 



INJURIOUS AND BENEFICIAL INSECTS OF CALIFORNIA. 



Fig. 74. — Peaeli twig showing 

 effects of an attack of the black 

 peach aphis, Aphis persicw-niger 

 Smith. (Courtesy of Prof. C. W. 

 Woodworth. ) 



Life History. — The insect winters over on the roots of peach trees, 

 where it may also be found in the summer. The first aphids appear 



above ground very early in the spring 

 and begin attacking the tender leaflets, 

 si loots or suckers, usually those at the 

 base of the tree or nearest the ground. 

 These first plant lice are all wingless. 

 As soon as the buds, young fruit and 

 leaves appear they are promptly at- 

 tacked, the entire crop often being almost 

 completely ruined. The leaves are curled 

 and weakened, while the young fruit is 

 so distorted as to be killed or rendered 

 unfit for market. During the months of 

 April and May winged migrator y 

 females appear, which start colonies 

 upon other trees. The work continues 

 until about the middle of July, when 

 most of the lice leave the tops and again 

 go to the roots. 



Nature of Work.— This species works 

 upon the young shoots, as well as the 

 roots of the host plants. 



Distribution.— This insect is at the 

 present time found in nearly every 

 peach-growing county in the State, and 

 may be expected to appear in practically every such locality. 



Food Plants. — The black peach aphis attacks the roots and foliage 

 of the peach and wild plum and the roots of almond, plum and prune, 

 when grafted on peach trees. 



Natural Enemies. — Internal hymenopterous parasites, the larvae of 

 syrphid flies and the green lacewing prey very effectually upon this 

 aphis. 



THE GREEN APPLE APHIS 



Apliis pomi De Geer 

 {Aphis mail Fabricius) 



In order that the readers may get a true idea of the development 

 and habits of plant lice the full life history of this species taken 

 largely from the investigations of Professor C. P. Gillette is given 

 as an example : 



Eggs.— We shall begin with the small black shiny eggs which are 

 found in great numbers on the smooth bark of the rapidly growing 

 twigs or water sprouts of the apple tree. When these eggs were first 

 deposited some time during the months of October, November, or as 

 late as December, they were of a beautiful green aolor, but with age 

 turned to a shiny metallic black. A careful examination in winter 

 of the young twigs and water sprouts of an orchard, which was 

 infested with this insect the previous summer, will often show great 

 numbers of these eggs, in some cases completely covering the twigs. 



The eggs themselves are very tiny, not nearly as large as a pin- 

 head, and are elongated or oval in shape. Only a small percentage 



