48 THE REPORT OF THE No. 19 



the wing hovering around the heads of sorghum in the early morning, evi- 

 dently awaiting the emergence of the females. The total length of the life 

 of the female is about 32 hours, that is to say, when facilities for the deposi- 

 tion of her eggs are given her soon after emergence. The males live about 

 half as long as the females. No attempts to breed this fly to maturity under 

 artificial conditions were successful. 



The egg is elongate in form and cylindrical, tapering towards the end 

 and is about .28 mm long and about .09 mm broad and resembles very 

 nearly the eggs of closely related species. It is laid by the female fly between 

 the glumes of the sorghum spikelet and on or very near the ovary of the 

 plant so that when the young larva develops it may find abundance of food 

 ready at hand without material need of any search. The injury to the ovary 

 of the plant is caused, evidently, by absorption of the juices of the ovary 

 by the larva which appears to carry out the extraction throughout the entire 

 length of its body. The larva when full grown is brick red in general color 

 and the developing pupa possesses the same characteristic shade. When the 

 period for transition from pupa to adult approaches, the pupa works its 

 way upwards and the emergence occurs at the apex of the glumes. After 

 emergence takes place, several seconds are allowed for wing development. 



I think I may mention here that there is, at present, in Louisiana an 

 extremely interesting but obnoxious little ant, Iridomyrme.v humilis, Mahr, 

 This ant is over-running the southern portion of the State and is having 

 considerable attention given to it by reason of its relationship to the agri- 

 cultural interests of the State. In the sorghum patch in which the experi- 

 ments with the sorghum midge were carried on this summer, this particu- 

 lar ant abounded. The ants were continually running about the leaves, 

 stems and heads of the sorghum plants attracted evidently by the sweet sap 

 of the plant and the excretions of the aphid which fed upon it. As the adult 

 fly is about to emerge from the pupa, the glumes of the plant are neces- 

 sarily forced slightly open and the ant, which is omnivorous, is thus allowed 

 to gain access to the helpless pupa. I actually observed an instance where 

 an ant bit off the terminal apex of the glumes and extracted the pupa. 

 Other instances were observed in which the ant was unable to make its way 

 to the enclosed pupa, probably, I suppose, on account of the glumes not 

 being sufficiently open and hence not allowing of a good hold. I have no 

 doubt that in a field in which this ant abounds, the death of many flies 

 may be accounted for. 



The total life-history of this species, according to Mr. C. R. Ball, varies 

 from 14 to 20 days. This summer it was estimated that it ran perhaps 

 somewhat longer, between 19 to 25 days. However, this is one of the points 

 that still awaits proof. The entire life-history takes place within the 

 sorghum flower, the egg being deposited there and the adult fly emerging 

 from it when the required developmental period is accomplished. The gen- 

 eral habits of this midge, therefore, can be seen to coincide very closely with 

 the habits of already studied and familiar species of the same genus and 

 closely related genera. 



In Louisiana this midge is heavily parasitised bv Aprostocetus diplosidus, 

 Crawford, This parasite is accompanied by a species of Tetrastichus which 

 Professor F. M. Webster considers as Drobably a secondary parasite. 



In reference to the distribution of the midge, I may say that it is more 

 generally to be found over the South than it was flrst thought. Early in 

 the summer it was known to exist in comparatively few States, but it now 

 appears th^t it has actually been found in Texas, Louisiana, Alabama, 

 Arkansas, Missouri and South Carolina. For the reason that this midge 



