()ctober 1913 



Sheep and Blowflies. 



The bloAvlly is oiw of llu- most 

 frisky of the \vin<i-e<i insects. Its 

 disturl)infr intluciicc on the oomlort 

 of mankind and our domestic ani- 

 mals demands a jjeneral crusade. 

 The blowfly takes care to ojyerate 

 on the sheep in places where the 

 animals cannot displace it. There 

 it ])ropa(jates its species, and the 

 only remedy the stockowner can 

 conceive is clippino- awa\i the wool 

 from the crutch of the animal and 

 applvinii some chemicals obnoxious 

 to the fly. While " crutchin<r " the 

 sheep in the manner described en- 

 tails much trouble and expense to 

 the flockmaster, it is not perman- 

 ently ellective. In fact, the em- 

 bryo of the flies is cut off with the 

 wool and permitted to seek cover 

 in the soil, when, in due course, 

 it ai^ain resuscitates into active 

 life countless number of the 

 species. As it seems humanlv; im- 

 possible to destroy all flies of anv 

 kind once they are enabled to take 

 flic^ht, it is therefore obviously es- 

 sential to endeavour to control the 

 sources. The New South Wales 

 Entomologist (Dr. Froesjatt) re- 

 cently said that durintr the last few 

 years many mixtures, dips, and 

 powders have been in use in all 

 parts of the State — with more or 

 less success as lasting cures — to 

 keep the flies from. blowin<r the 

 wool or reinfestin<j the wool t ve- 

 \-iously blown. The active proper- 

 ties of mo.st of these ware crude 

 oils, turpentine, tar, carbolic acid 

 in varioiis forms, and arsenic. 

 Many of these, rubbed in after the 

 damasred wool had been shorn off, 

 will drive the flies away for a 

 time, but none has been found that 

 will last for any lennfth of time. 

 The reason why these methods are 

 not permanently effective in ward- 

 ing off the persistent blowfly is 

 because the wool is always £frow- 

 mg ; and in a few weeks, or a 

 month or two, there is a laver of 

 new untreated wool below tlie 

 jToison — if there is any remaining 



— which willibc, shoidd the wool bc- 

 cotu>e damp or soiled, a safe fecd- 

 inc^ place for fresh majrjrioits. Con- 

 se(iuently it is very dilticult to find 

 anv dressing that can be lastinjj; 

 on close-wooUed sheep or ccaie 

 months before shcarinji', especiiiUv 

 when the .shec]) arc full-fleeced. The 

 damagre of the .sheep is caused bv 

 the maj^'gots of two common yel- 

 low blowflies found in both the 

 house and bush all the A'ear round. 



It is not a little remarkable 

 that farmers and graziers, when 

 dres-sing their sheep, never consider 

 the subsequent development of 

 blowflies which the operation may 

 cause. They throw on the ground 

 the damasred wool when cnitch- 

 ing, and scra,pe the maggots out 

 of the wounds. The maggots, if 

 nearly full-grown, burrow into the 

 soil, and rapidly change into 

 pupae. The previously so't, white 

 magTOt is then encased in a stiff 

 parchment-like .shell, where it can 

 remain safe and sotmd imtil suit- 

 able conditions arise. It then 

 bursts out of its protective cover- 

 ing and emerges a new-born blow- 

 fly. In summer the transformation 

 from masrgot to pupa, and pupa 

 to blowfly, is only a matter of 

 days ; whilst in winter it often 

 takes months. Every other blow- 

 fly maggot that escapes from the 

 bfown wool is capable of renro'd.uc- 

 ing a female blowfly that can de- 

 posit at the least loo e^gs — ^some- 

 tim.es double, that number — .several 

 times in the course of her few 

 weeks of life. Thus every well-de- 

 veloped maggot that is allowed to 

 live and get under cover when 

 " crutching " is being proceeded 

 ^vith means another flA^, and that 

 fly may mean hundreds more, ad 

 infinitum. Although the poison- 

 ous dressing fluid may fall upon 

 or be sprinkled over the maggots, 

 as is often the cage, if they can 

 get away from it into the soil 

 they soon work it all off their 

 skins, and wall suffer no damage 

 to stop them developing later. The 

 maggots and infested wool from 



every blown sheep shoidd be care- 

 fully collected and destroyed. Mr. 

 Froggatt considers this is quite 

 ])ractical. Each man shoidd have 

 a sheet, upon which the shec]) 

 should be jdaced while being 

 crutched or dressed. Everything 

 clipped from, or what drops from, 

 the sheeji could be caught on the 

 sheet, transferred to a bag, and 

 the contents shaken into a fire or 

 tub of boiling water. This method 

 would certainly go a long way 

 towards minimising the ])est. The 

 maggots from one crutching would 

 cause more trouble and expense, 

 subsisquently, than would pay 

 many times over for the precau- 

 tion in destroying them in the first 

 instance as described. Under the 

 ])resent thoughtless method of 

 crutching every sheepman is rein- 



(Continued on page 230). 



H. DENNIS 



IMPLEMENT MAKBB. 

 (Late of MORGAN). 



YOUNG STREET 



^ (Old Methodist Hall) between 

 PRA24KLIN & WAYMOUTH STS. 



DENNIS' PATENT 

 STEEL BUCKSCEAPEB AND SILT 

 SCOOPS, GATES. ETC. 



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