No. 394.] 



A BALLOON-MAKING FLY. 



811 



the balloon when the male is flying. It is frequently carried 

 farther back, apparently by the hind legs alone. Fig. 2 shows 

 the position assumed in copulation, the male underneath rolling 

 the balloon. 



No illustration could properly show the beauty of the balloon, 

 still less could anything worthy of the subject be made from 

 the shriveled and flattened specimens that now remain in our 



Fig 



possession. The half-tone (Fig. 3) serves only to show the way 

 it is formed of bubbles. 



The only published observations at all comparable with these 

 are on the European species of Hilara, a genus of Empidae 

 closely related to Empis, and especially on Hilara sartor 

 Becker. Several entomologists have published articles on the 

 species, and there has been considerable difference of opinion 

 as to the nature and purpose of the structure carried by the fly, 

 as well as the method of carrying it. Professor Mik, in the 



