REPORT OF THE SOCIETY 81 



Natural Enemies. 



Lady-bird beetles, syrphid maggots, lace-wing larvae, many parasitic 

 hymenoptera, nymphs of tree-crickets, harvest-spiders, birds. 



Control. 



Spray with kerosene emulsion, whale oil soap solution, tobacco extract, etc. 



CHIEF ECONOMIC SPECIES. 

 Common Cereal and Farm Crop Aphids. 



Apple Bud or Oat Aphis {Aphis avenae Fab.). — Sometimes called the Eu- 

 ropean Grain Aphis; is often injurious to apple buds and appears 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 generations, 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 Bakeri 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. Honey-tubes are short. 



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

 antennae and honey-tubes ; a row of black dots on each side of back. 



Corn Root Aphis {Aphis maidi-radicis Forh.) — Bluish-green lice on the roots 

 of corn, smartweed and other weeds; attended by brown ant {Lasius niger) . (See 

 Farmers' Bui. 891, U.S. Dept. Ag.). 



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 {Macrosiphum granarium Kirby). — Occurs on wheat, 

 barley and the grasses, Agrostis, Bromus, Dactylis, Poa and Phleum and Cat-tail. 

 Widely distributed in the U.S. 



