28 CROP PEST COMMISSION OF 



brood of this species in a season, for Hart's specimens issued in 

 August and September, while I have bred specimens which is- 

 sued in July. This is a very small insect, and passes its immature 

 stages inside the eggs of the fly, one specimen in each egg. At 

 a certain place in Medina County, Ohio, where the eggs of the 

 bJack horsefly were common, it was found that many of the 

 masses remained plump long after others had shriveled because 

 of the larvae hatching from them. An investigation showed that 



FIG. 1"). Horsefly egg-parasite, Phanurux tabniiivorux. inurh enlarged. ( Aft^r 

 Hart, Bull. Ills. State Lab., Volume IV.) 



the former contained many parasitized eggs, some masses having 

 nearly- every -specimen in this condition. A number were col- 

 lected and put into small vials, where, in the course of a couple 

 of weeks, hundreds of the parasites issued. What I have ob- 

 served regarding this minute species proves to my mind that 

 it is of much importance in lessening the numbers of horseflies 

 \vhose eggs it infests. It has not been observed in Louisiana, but 



