﻿THE CATTLE GEUBS OE OX WARBLES 60 



the abdomen is extended and retracted and the insect makes clumsy 

 attempts at flight. Within half an hour after emergence it is able 

 to sustain itself on wing, though rather clumsily. 



The adults evince a very strong positive heliotropism. In cap- 

 tivity their main energies are devoted toward escaping. Very 

 few flies have been recovered in nature unless in the act of attack- 

 ing cattle, and just what place they choose for resting is not known. 

 Apparently, however, they remain on the ground or on grass and 

 shrubbery close to the ground. 



PROPORTION OF SEXES 



The sexes were noted in the case of 284 reared adults of II. 

 lineatum. Of these, 147, or 51.8 per cent, were males. The males 

 usually emerge from the puparia slightly before the females, al- 

 though this is not uniformly the case. Among 172 adults of //. 

 Ijovis which were reared and the sex noted, 81, or 47.1 per cent, 

 were males. 



FOOD OF THE ADULT 



Mention has been made of the suppl}' of food carried over to 

 the adult stage from the larvse. This appears to be sufficient to 

 meet the needs of the adult insect throughout its life. The Avriters 

 have repeatedh' attempted to feed reared adults in captivity on 

 fruit, sirup, and water, but have never observed any indication that 

 they would partake of such substances. The mouthparts are de- 

 generate and probably not capable of functioning in feeding. 



MATING 



Many reared flies of II. lineatv/rri have been kept in various types 

 of breeding cages, usually supplied with sticks or branches of green 

 trees, and in the much greater number of these cases mating was 

 not observed to take place. Although a number of these reared 

 females were induced to oviposit, in most instances the eggs were 

 infertile. In four cases mating was closely observed. The act 

 usually took place immediately after the males and females were 

 placed in the same small cage. In each instance the male seized the 

 female as soon as they met, but in one case the male went through 

 some preliminary courting actions. He crawled over the female's 

 back and head, then worked rearward on the back of the female and 

 mating began. The details of mating appear to be about the same 

 as with many other Diptera. Tlie duration of the act ranges from 

 one to three minutes. In two instances mating was repeated a second 

 time immediately after the first. In two of the four instances of unit- 

 ing obseiwed in //. lineatnTn both the male and female were 1 day 

 or more old. In the other instance, however, which occurred at 

 10.45 a. m., the male had emerged shoilly prior to 9. a. m. of the 

 same day, and the female was observed to crawl from the puparium 

 at 10 a. m. ; thus mating took place when the female had been out 

 only 45 minutes. It is interesting lo note in this connection that 

 this female upon })eing placed on a calf 20 minutes nftcr mating 

 deposited a considerabh! niunber of fertile eggs. 



//. homn evidently mates nnu-h more freely in cajjiivity than 

 IJ. lineatuin. The act has Ijeen observed in many instances to take 



