206 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 3 



Kaffir Corn, Broom Corn, Milo ]Maize and Johnson Grass {Sorghum 

 halapense) . 



In one instance the writer induced this midge to oviposit within the 

 seed of the common Fox tail grass {Setaria glauca); although the 

 latter had not been listed among the hosts of C. sorghicola Coq. 



The females oviposit within the seed glumes, placing the eggs close 

 to the ovary. The newly hatched larva:? absorb the plant juices from 

 the ovary and remain close against the latter until they have com- 

 pleted their growth and transformed into pupa?. The pupa? work 

 their way upwards from the ovary until the apex of the seed is 

 reached. There they remain until the adult is ready to emerge. At 

 that time the pupa? work their way still farther up until about two- 

 thirds of their length projects from the apex of the seed. In this 

 position the adult liberates itself, leaving the cast pupal skin attached 

 to the spikelet. 



The larva? are not cannabalistic ; often as many as six in different 

 stages of growth are found within a single seed while the writer has 

 frequently removed eggs, larvae and pupa from one seed. 



The Sorghum Midge is most thorough in its destruction of a crop 

 of seed. In Midge infested sections rarely less than 90% of the 

 growing seed are infested during the height of the season. The first 

 and last heads are the ones least infested. 



Copulation takes place immediately after emergence of the adult, 

 the males hovering about the sorghum heads and seizing the females 

 as fast as the latter leave the pupal skin — often before their wings 

 have dried sufficiently for' flight. 



■Immediately after copulation and when the wings are sufficiently 

 dr>' for flight the females begin ovipositing. This is continued ener- 

 getically until the quota of eggs has been deposited. 



The time required for development from egg to imago varies con- 

 siderably and is largely controlled by prevailing temperature and 

 humidity. In the low country of southern Louisiana the time was 

 much longer than in south central Texas where the heat is extreme 

 and humidity very low. 



The parasite, Aprostocetus diplosidis Crawford, is the predominant 

 Midge parasite in Louisiana. During the summer of 1908 this para- 

 site was successfully introduced into the fields around San Antonio, 

 Texas, by Prof. F. M. Webster through the cooperation of Prof. 

 "Wilmon Newell of the Louisiana Crop Pest Commission. 



Tetrastichus sp. Craw, has been bred from Midge infested sorghum 

 seed by the writer along with the parasite Aprostocetus diplosidis 

 Craw. 



