224 MR. A. M. ALTSON ON THE LIFE-HISTORY AND 



and veacliing around again with the tip of his abdomen to gain 

 entrance into the vaginal oritice. Or, on the otiier hand, he may 

 simply back quickly to the. caudal end of the feiuale and attempt 

 union. In one cuse, .... coition lasted for fourteen seconds, 

 in another for ten seconds. Mating is promiscuous for both 

 sexes." (6.) 



During the breeding operations, when females were scarce — 

 being occupied with host puparia, — the writer has frequently 

 observed an unresponsive female crawling aboiit with several 

 males upon her, the lower ones holding on dorsally and laterally, 

 and those above holding on to each other. Sometimes the female 

 with this load on her would try to climb the side of the cage. 

 This efibrt always ended in the whole party falling to the bottom. 

 On three specific occasions the number of males thus congregated 

 numl)ered 10, 7, and 11. 



The males have some curious habits. When the puparia from 

 which adults have commenced to emerge are lying unburied on 

 soil, a male can be observed to take possession of one, and either 

 stand on it waiting for a newly-emerged female to appear, or he 

 will enter it and periodically make an appearance to seek a mate. 

 Generally the males remain in the immediate vicinity of the 

 Duparia from which emergence is taking place, and running over 

 and around these in search of females, they are continually 

 meeting each other ; then they start to fight. This usually takes 

 place by means of the antennse and fore legs, resulting frequently 

 in the loss of a few joints of the flagella by one or both antago- 

 nists. During these scuffles there were sometimes three or four 

 participants, and then it frequently happened that a puparium 

 became dislodged, with comical results if it was occupied by a 

 "domesticated" male: he would sally forth and attack the first 

 within reach; generally one in no way responsible for his dis- 

 couifort. From a short distance the whole area occupied by the 

 males seemed to consist of combatants. 



Females only resorted to fighting when disturbed during 

 •oviposition ; seldom did males venture into the dishes containing 

 host puparia for parasitization. 



Plight. — The females, in spite of their large wings, are only 

 ■capable of flying short distances, in a very jerky manner, about 

 6 feet at a time at most. Before starting on a flight, they usually 

 indulge in a few preliminary movements of their wings. Their 

 most customary method of progress is to crawl. 



The males are quite incapable of flight, and the only occasions 

 ■on which they have been observed to use their wings are when 

 courting and fighting. 



Oviposition. — This takes place within a host puparium, prefer- 

 ence being shown for those between 24 to 72 houi's old — that is to 

 say, afterhistogenesis has started and the developing fly-nymph 

 is covered in its pupal skin and free of the puparium except 

 where attached anteriorly and postei-iorly by the tracheje. A 

 female will not oviposit in a puparium containing an atrophied 



