132 Second Report on Economic Zoology 



Notes on the Sheep Nasal Fly {(Estms ovis). 



The following inJormatioii has also been ,?eut the Board concerning 

 the Sheep Nasal Fly, which is more or less prevalent all over (rreat 

 Britain : — 



" This fly is sometimes erroneously called the Sheep Gad Fly. 

 Bracey Clarke, Steel an<l others wrote upon it under this name, and 

 hence, except l)y Miss Ormerod, the name has been carried on in 

 print. The Gad or Breeze Flies are Tahanida', a perfectly distinct 

 family from the QJsfridie. or Warble Flies. The Gad Flies, Bree7>e 

 Flies or Brimps cause annoyance by ' biting ' animals. Their larva^ 

 are harndess. In the Warble Flies or (Estridse. it is vice versa. The 

 name Sheep Gad Fly is wrong both scientihcally and in popular 

 parlance. 



" The adult has also been wrongly described as being ' something 

 like an overgrown House Fly.' This statement was made undoubtedly 

 as a slip by Biley thirty-five years ago, and should not be copied, as 

 there are flies which are found in connection with sheep that have an 

 appearance something like the ' House Fly,' whereas the Sheep ' Nasal 

 Fly ' has not. The (Estridie and the Muscidse ha^e nothing in 

 common. 



" The description of the Sheep Nasal Fly ((Estrus ovis) is as 

 follows : ' Head, pale brown ; thorax, pale brown to ashy grey, 

 mottled and spotted with Idack spot-like tubercles; abdomen, dull 

 brownish to slaty grey, sometimes appearing ash-grey with dusky 

 spots and with a dull silvery slieen when alive ; legs, pale tavrny to 

 yellowish brown. The wings are t^uite colourless and transparent, 

 the poisers or halteres almost white and covered by tlie large basal 

 alula or winglet, a flap-like structure at the base of the wings.' Both 

 males and females fly about on ^^arm sunny days for the purposes of 

 copulation, etc. 



" On two occasions " maggotty heads ' have been sent me in which 

 the larva were found in March varying from -i mm. up to the mature 

 size. This clearly points to parthenogenetic reproduction. 



" The Sheep Nasal Fly certainly deposits its eggs on the nostrils 

 of the sheep, for 1 have on several occasions observed the curved ova 

 in and around the nostrils. Brauer, however, was inclined to believe 

 that the young were hatched alive, so probaljJy both eggs and young 

 are produced. 



" The larva use their hooks and \ entral suckers to aid their 

 progress, and also their two anal papilla. ]\Iiss Ormerod pointed 



