592 INSECT PESTS OF FARM, GARDEN AND ORCHARD 



Plum Aphids 



Three species of aphids are common on the plum foliage in 

 spring and fall, and often do serious damage by curling up the 

 foliage in the spring and causing it to drop prematurely, thus 

 checking the growth of the tree and preventing proper fruiting. 

 The life histories of the three species are very similar in that the 

 eggs are laid upon the plum in the fall, upon which two or three 

 generations develop in the spring, but in early summer they 

 migrate to other food-plants, from which they return to the plum 

 in the fall. The life history is much the same as that of the 

 apple-aphis, and green peach-aphis, and need not be rehearsed 

 in detail. 



The Mealy Plum-louse * 



This is a light-green species which is covered by a bluish- white 

 mealy powder. It has a long narrow body, one-tenth inch long, 



FIG. 520. The mealy plum louse (Hyalopterus arundinis Fab.): a, young 

 nymph; b, last stage of nymph of winged form; c, winged viviparous 

 female all much enlarged. (After Lowe.) 



marked with three longitudinal stripes of a darker green. The 

 honey-tubes are short, thick, and slightly constricted at the base. 

 The winged female is similar in coloration except that the abdomen 

 bears several transverse triangular marks of darker green. In 

 June the winged females migrate to certain grasses upon which 

 the aphids reproduce during the summer, though small colonies 



* Hyalopterus arundinis Fab. Family Aphididce. W. D. Hunter in 

 Bulletin 60, Iowa Agr. Exp. Sta., p. 92, states that Aphis prunifolice Fitch 

 is probably the same species. Certainly H. arundinis and pruni, Aphis 

 pruni and prunifolice, seem to have been applied to the same species in the 

 economic literature in America. See Lowe, V. L., Bulletin 139, N. Y. Agr. 

 Exp. Sta., p. 657, and W. M. Davidson, Bulletin 774, U. S. Dept. Agr. 



