310 SOME INSECTS OF ECONOMIC IMPORTANCE. 



about farm buildings and fences, etc., around fields from 

 August to October. It sucks the blood of horses, cattle, 

 and human beings. The bite is painful. 



(b) The Cleg or Brimp. A well-known fly attacking 

 horses and cattle during the warmer months. Only the 

 females are blood- sucking. This fly has dusky spotted 

 wings, body flattish and blunt behind. The head is much 

 broader than long, and somewhat cresceiitic. A pair of 

 feelers stand out in front, the terminal parts of which 

 curve slightly outward. The fly of course does not sting 

 when handled. The proboscis is not visible from above. 



(c) The Gad or Breeze fly. Very similar to the fore- 

 going but larger. Head is even more crescentic, and 

 antennae shorter than in the former, but with a distinct 

 notch and curved tip. They bite cattle severely. Common 

 near woods. 



2. Parasitic Flies. 



(a) Bot flies. These are medium sized, hairy flies 

 which deposit their eggs on the fore parts of horses. 

 When the maggots emerge, the horse licks the place and 

 swallows the maggots. These on reaching the stomach 

 attach themselves, feeding and growing ; they live here for 

 about ten months. At the end of this period they pass to 

 the outside along with the undigested food and pupate on 

 the ground. In the course of a few weeks the adult flies 

 emerge from the pupal cases and the life cycle recommences. 



(b) Sheep's nostril fly. A similar fly attacks sheep, 

 depositing its eggs on the nose or face. The maggots 

 creep into the nostrils, and in the upper spaces live for 

 about the same time as the bot flies in the horse, feeding 

 on the secretions of the cavity in which they lie. Their 

 presence may cause difficulty in breathing, giddiness, and 

 often a high stepping gait in the sheep. When the larval 

 period is over the sheep is able to snort them out upon the 

 ground, where they complete the pupal period in a few 

 weeks. Sometimes the health of the sheep deteriorates so 

 much that slaughter becomes necessary. 



