FIELD CROP INSECTS 



247 



about one-tenth inch long, with black antennae as long as, or 

 longer than, the body. They are a yellowish-green color and 

 the long nectaries projecting from either side of the abdomen 

 are black. The winged females are about the same length, 

 the antennae are a third longer than the body, which is of 

 the same general coloration except that the lobes of the 

 thorax are brownish or blackish and the abdomen is marked 

 with four or five 

 transverse blackish 

 spots in front of 

 the nectaries. 



The German 

 Grain-aphis* is 

 commonly associ- 

 ated with this spe- 

 cies and has very 

 similar habits. It 

 may be distin- 

 guished by its lack- 

 ing the blackish 

 markings on the 

 abdominal seg- 

 ments. 



These aphides 

 appear on the 



young wheat in the spring and multiply rapidly on the 

 leaves until the grain commences to head, when they crowd 

 among the ripening kernels. As the small grains ripen the 

 aphides migrate to various grasses and are not in evidence 

 during summer, but later migrate to volunteer oats and 

 wheat, upon which they breed until fall wheat is avail- 

 able. 



* Macrosiphum cerealis Kalt. 



FIG. 172. The German grain-aphis (Macro- 

 siphum cerealis Kalt). (After Riley, U. S. 

 Dept. Agr.) 



a, winged migrant; b, nymph of same; c, wing- 

 less parthenogenetic female; d, same showing exit 

 hole of parasite enlarged. 



