APHIDS 



53 



STRAWBERRY 



The Straw Iierry Root Aphis 



Aphis forhesi Weed 



This species Is very destructive to 

 strawberry plants in the eastern and mid- 

 dle western states. The lice, which are 

 greenish-black and about one-twentieth 

 of an inch long, cluster in great numbers 

 on the larger roots. The winter eggs 

 are laid above ground but the lice work 

 chiefly under the surface of the ground 

 and are especially troublesome in light 

 soils. In the control of this aphis sev- 

 eral points should be noted: First, 

 plants should not be set out on land in- 

 fested within the two years previous, as 

 infested roots were probably left in the 

 soil when the plants were pulled up and 

 these remain infested for months; second, 

 plants to be set out, if infested, may be 

 disinfected by being dipped In diluted 

 tobacco extract, provided the winter eggs 

 have hatched: third, straw burnt over 

 the beds just as the plants are beginning 

 to grow in spring will destroy eggs and 

 lice on the leaves and stems. Several 

 species of plant lice occur occasionally 

 on the leaves of the strawberry. These 

 can be destroyed by any of the contact 

 insecticides suggested for the Green Apple 

 Aphis. In Europe Schizoneura fodiens 

 Buckt. infests the roots of the straw- 

 berry. "' 



BLACKBERRY AXl) RASPBERRY 



The Blackberry .4phis 



Amphoropliora rtibi Kalt. 



This is a large pale green louse with 

 dilated cornicles. It is a European 

 species and occasionally colonizes the 

 growing shoots of blackberries and rasp- 

 berries in spring. Its life history is not 

 well known. It may be controlled by 

 spraying with whale-oil soap 1 pound to 

 6 gallons of water. 



WALAUT 



The European Walnut .Vphis 



Chromaphis jufjlanrlicola Kalt. 



This Is a small lemon-yellow species 

 occurring on nuts and leaves of the 

 European walnut. Its life history is 

 similar to that of the Green Apple Aphis 



except that the agamic or viviparous lice 

 are all winged. The winter eggs are 

 often laid in crevices of the bark and 

 are thus not easily reached by spraying. 

 The lice on the leaves can be controlled 

 by spraying with a combination spray 

 of dilute oil emulsion and tobacco ex- 

 tract (Black Leaf "40", 1-1,600, or Black 

 Leaf 1-100). 



CHESTNUT 



The Chestnut Aphis 



Callipteriis castaneas Buckt. 



This species infests the leaves of com- 

 mercial chestnuts. In appearance and 

 habits it greatly resembles the walnut 

 louse. Doubtless it can be controlled in 

 a similar manner. 



CITRUS TREES 



In America five species of plant lice 

 are found on citrus fruits. They are (1) 

 the Citrus Aphis ( Toxoptera aurantiae 

 Koch); (2) the Cotton Aphis (Aphis 

 gossypii Glover); (3) Aphis cookii Essig; 

 (4) the Green Peach Aphis (Myzus persi- 

 cae Sulz.) : (5) Macrosiphum citrifolii 

 Ashm. The first three of these are small 

 dark brown or black insects while the 

 last is a larger pale green form. The 

 Green Peach Aphis will be found de- 

 scribed under the article on Peach plant- 

 lice. Occasionally one or more of these 

 lice become abundant on the tender 

 growth of citrus foliage and may do much 

 injury to young buds. As far as citrus 

 trees are concerned the life histories of 

 these species have not been entirely 

 worked out. 



Control 



Whale-oil soap. 1 pound to 6 gallons of 

 water, 7 per cent kerosene oil emulsion, 

 soap and dilute tobacco extract, or car- 

 bolic acid emulsion (diluted so that about 

 I'i gallons crude carbolic acid is used 

 to 200 gallons of water) will be found 

 effective washes for citrus plant-lice. A 

 second application may be necessary 

 about four days after the first in order 

 to insure the complete control. High 

 pressure is requisite except for young 

 buds, which should be sprayed with a 

 knapsack or bucket-pump as pressure will 

 knock them off the tree. 



