ORDER HYMENOPTERA 



299 



tents of which are not equal to a drop of water. However, 

 the parasite may feed upon the aphid during some httle 

 time and is supplied with food from the efforts of the aphid 



Fig. 240. — Wingless female of "green V)Ug" containing larva of the 

 parasite Lysiphlebus tritici. Much enlarged. (W'ebster, Div. Ent., U. S. 

 Dept. Ag.) 



sucking nutriment from the plant. This species is consid- 

 ered one of the principal agents in control of the spring grain 

 aphis or the "green bug" which during recent years has 



Fig. 241. — Lysiphlebus depositing its eggs in the l^ody of a grain aphis. 

 Much enlarged. (Webster, Div. Ent., U. S. Dept. Ag.) 



caused extensive injury to the wheat crop in the south- 

 western part of the country. Its attack seems to be dis- 

 tributed, however, over a number of si)ecies and it is therefore 



