lo June. 191 l] }Iaggot Flyin^heep^ 4^ 



MAGGOT FLY IN SHEEP. 



H. ir. Ham, Sheep Expert. 



The fly chieflv accountable for this trouble is the Common Yellow Blow 

 Fly; while the Blue Bottle Fly, in some parts, is also responsible, but 

 not to the same extent. The first serious trouble met with by the writer, 

 through this pest, was about 1897 in rabbit- infested timbered land on 

 the calm warm eastern slopes of the You Yangs, between Melbourne and 

 Geelong. On the Lachlan River, north of Hillston, New South Wales, 

 no serious trouble was experienced until after the break up of the main 

 drought in 1902, and following the almost total destruction of rabbits 

 by poisoning and loss of stock through shortage of water. The scourge 

 gradually manifested itself, .and from then the practice has grown for each 

 boundary rider to carry shears, a necessity previously unknown. 



About the year 1894 it was considered that an advantage would be 

 gained by increasing the weight per head and the covering of our merino 

 flocks, for the lightest and best merino wool was unprofitably low in value, 

 top grades of Mctorian and New South Wales wool realizing no higher 

 than 7id. to 8id. per lb. Second class merino wool was worth from 6d. 

 to 7d., and sheep growing this wool could be easily made to give the 

 greatest weights. There was no indication that these prices would not 

 continue, for up to then there had been good seasons. This was the 

 commencement of the demand for dense heavy cutting excessively covered 

 sheep; and a special point developed was the filling in with wool about the 

 breech and tail. 



W'itli the advent of the maggot fly, this became a disadvantage, as 

 the wool acted as a place of lodgment for fluids passing from the body ; 

 for example, when scouring, especially in weaners ; and, in the case of 

 ewes, through liquids soaking the wool at time of lambing. This is most 

 noticeable in .seasons when ewes have greater difficulty in cleaning, conse- 

 quent on their low condition. Well bred merino ewes are most subject 

 to attack by the fly, particularly those that are weak and overloaded 

 with wool, while the bare pointed Leicester type of sheep suft'ers the 

 least. 



\\'holcsalc destruction of rabbits has been, no doubt, a factor in 

 increasing the number of flies ; and to this must be added the carcases of 

 stock, which afford a .splendid breeding ground. Further, the natural 

 enemies of the fly have decreased. Ring-barking of trees, bush fires, and 

 other causes have discouraged the increa.se of bird life, and underground 

 enemies such as lizards, iguanas, &c. It is no uncommon thing, in the 

 autumn, to find thousands of the brown ca.ses, from which the young flies 

 have developed, in the dust about and under where carca.ses have dried. 

 The maggot takes about a week to attain full size and a fortnight to 

 <leveIoi) into a blow fly. The.se periods vary according to weather condi- 

 tions. Insufficient moistun- in the soil or heat too inten.se is not favourable 

 to its dfvel(j|)ment, but suflicient moisture for the purpo.se is usuallv 

 su|)plied from the decomposing carcases. 



The seasons in which the di.scharge from weaners and lambing ewt s 

 i< greatest are usually the most favourable for economical destruction of 

 raijbits; and. if early autumn xa\u<. iMcur. j)erfect conditions for the 

 breediii'r of flics are created. 



