3rar, 2, 1908.] Agricultural Gazette of N.S. W. 229 



The Bot-fly {Gasteropluhcs eqiu). 



WALTER W. FKOGGATT,*^ 

 Government Entomologist. 



As several notices have recently appeared ia the newspapers stating that the 

 " Bot-llies " are causing the death of horses in the southern districts of 

 New South Wales, it is advisable for everyone to be on the look out for 

 them for the season is rapidly approaching when, if there are any of these 

 pests in the neighbourhood, tlif^y will emerge from the dormant pup:-e buried 

 in the soil and deposit their eggs upon liorses. 



I tlier^fore propose in these notes to give some account oP these flies, their 

 habits and life-history, so that farmers and others interested in stock can 

 recognise both the larval " bots " and mature flies when they c 'me across 

 them. 



There is no record of bot-flies having been found in tlie iioithern disiricts 

 of this Colony, and the chief area of infes'ation is around Wagga, Bombala, 

 on to the Victorian border; but, at the same time, I have seen portions of 

 the stomach of a horse killed at Botany that were thickly covered wiih the 

 bots, so that it is probable that bots are much more common than is generally 

 suspected. 



The ))ot-flies belong to the family (Estridcp, which contains a number of 

 rather large flies with very short antennae and the front of the head standing 

 out. They are distinguislied from all other flies by having the mouth parts 

 obsolete or aborted, and only repre-ented by two or three flesliy tubercles 

 (except in several of the minor genera), and 'hey all have stout wing-! with 

 few veins. These flies lay their eiigs or larvte upon the liairs oi" skin of 

 different animal-, fr.mi which position they work their way through the skin, 

 or gain an entrance into the mouth (by means of the animal licking itself), 

 aid make their way into the internal organs. WestA'ood grouped the 

 (Estridm under three heads — cutaneous, the warble flies ; cerv'wil, those 

 attacking the nasal cavities ; and gastric, those found in the stomach. Those 

 whose larvie live l)eneath the skin are generally known as " warbles," as the 

 "ox warble" (^llypoderma litieatd). In this case the eggs are licked ofl[' the 

 hairs of the animal they infest, and thus cai-ried into the mouth ; but instead 

 of making for the st )mach, they work their way through the tissue to a point 

 immediately beneath the skin, wh-re they remain stationary, forming a warble 

 or lum|) from which thn fly makes its escape through the skin, leaving behind 



[* As numerous inquiries for information regarding "Bot-flies" have been made, and as 

 the stock of November, 1900, (raze<<*« and pamphlets is exhausted, Mr. Froggatt's notes 

 are republished. At present Mr. Frogi^att, the Government P^ntomologist, is absent 

 from Australia in quest of information regarding insect pests ; there is, therefore, no 

 opportunity for him to supply additional notes on the subject. — Stb-Ed.] 



