MINUTE WORMS WORKING IN THE SEED 



219 



The Sorghum Midge {Contarinia sorghicola Coq.) 



Heads of sorghum are attacked by the larva of a minute two- 

 winged insect or " midge," preventing the formation of seed. If 

 infested heads are examined, the seeds will be found shriveled, while 

 beside them may be seen a tiny grub. Profitable crops of seed can- 

 not be secured where the midge is abundant. 



The first generations of the midge are passed in other plants that 

 mature heads earlier, notably Johnson grass. By the time the sor- 

 ghum is sufficiently mature the midges are numerous. Eggs are laid 

 witliin the developing seeds. 



Remedial measures include destruction of Johnson grass, and clean 

 harvesting in the fall. 



The Clover Flower-midge {Dasijneura leguminicola Lint.) 



The presence of the clover 

 flower-midge is recognized by 

 the fact that the florets of clover 

 bloom fail to develop normally, 

 become shrunken, and the whole 

 head lacks color. 



The adult insect is a minute, 

 gnatlike creature with long legs 

 and dusky wings. Eggs are laid 

 in the clover head, and the larva 

 feeds in the ovaries, preventing 

 the normal expansion of the floret 

 and the development of seed. 

 A pupal stage is passed in the 

 ground, followed by a second 

 brood at the time of the second 

 blooming of clover. Winter is 

 passed in the soil. 



In fields containing mostly 

 clover and httle timothy it is 



Fig. 272. — Clover head showing irregu- 

 lar blooming caused by the Clover 

 Flower-midge. Original. 



