1907.] 231 



orange dry, and overv now and again lurniug it about to insert her 

 beak in a fresh spot. 



The insects victimized were as follows : — 



June 9th. — From 5 pairs in cop ; 3 Perlids, 2 Bibio varipes. 

 „ 11th. — „ G visiting (J '3 ; 5 Perlids, 1 Ephemcritl. 

 „ 11th. — ,, 11 ^'s in cop. ; 6 Perlids, 4 Ephcincrids, I Tipulid. 

 „ 14th. — ,, 1 visiting d ; 1 Pcrlid. 

 „ 14th.— ,, 1 $ in cop.; I Perlid. 

 „ loth. — „ 1 c? sitting on grass ; 1 Bibio oaripe.t. 



It is unlikely that the male makes this offering at the shrine of 

 his divinity from purely altruistic motives ; it may be that the pre}"^ 

 functions as a kind of adventitious " sexual adornment,"* or as 

 a bribe to secure his personal safety, while on the other hand it 

 appears not unlikely that various suggestions with regard to Culicidce, 

 Tabanidce, and other blood-sucking flies, aneut the existence ot" some 

 definite physiological connection between the ingestion of animal 

 juices and the process of reproduction, may ultimately be found to 

 have some bearing on the case. 



In this species {U. horeaUs) pairing seemed not to occur later 

 than 6 o'clock, but about sunset (9 — 9.45 p.m.) I found Rilara maura 

 in a dancing crowd (in which both sexes were present) ten to fifteen 

 feet above the surface of the burn. They were too high for the net, 

 but every now and then an individual could be seen flying with a 

 jerky undulating motion, when one of those above would fly down 

 to it and copulation would ensue (this reminding one much of the 

 motions of E. horealis prior to coupling). The pair then, instead of 

 settling, proceeded with steady level flight along the course of the 

 burn, about ten feet from the surface, and by standing in mid-stream 

 I was able, during thi-ee evenings, to catch thirty-three pairs. From 

 twenty-six of these I took prey, and this was in possession of the 

 female in all those cases (about half the total number) in which it 

 had not been relinquished before I was able to determine the owner. 

 Out of several males, captured when flying casually about (not in the 

 dance), four had prey, but only in one case was it unvvounded, the 

 other three having evidently been sucked. 



As I could not succeed in catching any of the males just as 

 copulation api)eared imminent, I was unable to arrive at any definite 

 conclusions regarding the disposal of the prey in this species. On 



* Aldrich and Turley, in their account of the " Balloon-Making Empid," say that the female 

 is attracted by the size of the balloon carried by the male ; that the balloon frequently contains an 

 insect, but that balloon and (presumably) insect are dropped as soon as copulation takes place. 



