142 ECONOMIC ENTOMOLOGY 



before the other apple aphids. Stem-mothers appear early in May and 

 are yellowish-green with three dark lines on back; progeny winged and 

 blackish; migrate to grains and grasses in the second and third genera- 

 tions, winged and wingless generations. Migrate back to apple in 

 September where mating occurs. Males produced on the secondary 

 host and females on the primary host. Beak short and stout; thoracic 

 shield dark; cornicles short and flanged; cornicles, antennae and feet 

 black. 



Clover Aphis {Aphis baker i Cowan). — Sometimes attacks the apple 

 in the middle West. Eggs are laid on the apple, the pink stem-mothers 

 appear early and give rise to green winged and wingless forms. The 

 former migrate to clovers and give rise to several wingless generations. 

 In late autumn the winged forms fly back to the apple and hawthorn 

 where the eggs are laid. Cornicles are short. 



Com Leaf Aphis {Aphis maidis Fitch).- — Bluish-green, with black 

 legs, antennae and cornicles; a row of black dots on each side of 

 back. 



Com Root Aphis {Aphis maidi-radicis Forb.). — Bluish-green lice on 

 corn roots; attended by brown ant {Lasius niger). 



Spring Grain Aphis or Green Bug {Toxoptera graminum Rond.). — 

 Infests cereals in spring; wingless form yellowish-green, with faint dark 

 line along back; eyes black. Winged form larger, with darker thorax. 

 Migrates to other regions and to grasses. Parasitized by Lysiphlebus 

 tritici. 



Western Grain Aphis {Brachycolus tritici Gillette). — Is injurious 

 to winter wheat in Montana. 



English Grain Aphis {M acrosiphum granarium Kir by) . — Occurs on 

 wheat, barley and the grasses, Agrostis, Bromus, Dactylis, Poa and 

 Phleum and Cat-tail, widely distributed in the U. S. 



COMMON FRUIT APHIDS 



Apple Bud or Oat Aphis {Aphis avencB Fab.). — See above. 



Green Apple Aphis {Aphis mali Fab. = A. pomi DeG.). — This 

 aphis collects usually on the tips of tender shoots, on the under surface 

 of the leaves, and when abundant attacks the developing fruit. 

 Winters on twigs as black shining eggs which hatch just before leaf 

 buds open; Jf 2 irich long, pear-shaped; bright green; black, slender 



