30 THE BOOK OF THE FLY 



painful bites of a newly attached forest-fly, but one 

 can only wonder at the frantic galloping of oxen and 

 horses to and fro when a non-biting cestrid fly buzzes 

 about like a harmless fat bumble bee and slowly 

 approaches. 



The females of all the worble-flies, the nostril-flies, 

 and the bot-fly are short-lived, appearing on the wing 

 in August, possibly seen a few days earlier. In the 

 act of ovipositing they make themselves very con- 

 spicuous ; they lay their eggs whilst hovering in the 

 air, their extruded ovipositors attaching glutinous eggs 

 to their victims. The hatching of the eggs of the 

 bot-fly! is assisted by the habit of animals to lick 

 themselves and each other, when certainly their warm, 

 moist tongues will convey into their mouths the newly 

 emerged bot-fly's maggots, which many months later 

 are to be found attached to the internal lining of the 

 unwilling host's stomach. When fully grown in June, 

 these maggots loosen their hold, are discharged with 

 the dung, and pupate in the soil. 



No satisfactory account has yet been given as to the 

 early stages of the maggots of the worble-flies. The 

 eggs, having been attached to hairs on the host's hide 

 in August, the prominent round pustulent swellings, 

 called worbles, wherein the maggots dwell, do not 

 become conspicuous until the following months of 

 April and May. It is a reasonable surmise that the 

 obscure and long first-period of the maggot's existence 

 may more or less conform to that of some of those 

 flies which are also single-brooded but are predaceous 

 or parasitic on insects. The newly hatched maggot 

 perhaps can crawl, but does not feed until after several 



