BLOW FLY PARASITES.

Hauraki Plains Gazette, Volume XXXX, Issue 5372, 9 January 1929, Page 1

BLOW FLY PARASITES.

A SERIOUS PROBLEM. SOLUTION IN SIGHT. Enlarging upon the paragraph refcently published about the work of the Cawthorn Institute in breeding parasites that are destined to put an end to the ravages of the blow fly, the Nelson Evening Mail stated that one of the most serious problems that the qheep farmer has, to meet, both in Australia and New Zealand is the infestation of live sheep by the mag-' gots or blow fliesi No dip at present on the market is effective in either preventing or Controlling, the maggots on the animals. In actual figures the depredation of these insects cost New Zealand in the vicinity of £400,600 and Australia £2,000,000 annually. Among merino sheep the trouble is •more pronounced, and in New Zealand it is therefore a greater problem in the merino- country of the South Island. than in the North Island, where long-woolled rjheep predominate. Owing to the ineffic.acy of dips, the control of maggots by means of a natural enemy was undertaken in 1926 by Dr. Miller, • chief of the entomological department Cawthorn Institute, when holding the position of New Zealand Government Entomo-, logist. In different parts of the world there are over. 30 known species o.f natural enemies to blow flies. Of thosei t was decided .to import from England the maggot fly known as Alysia mandueator. Through the agency of Dr. G. Marshall, director of the Imperial Bureau of Entomology, London, of the parasite were received n New Zealand towardls the close of 1926. These shipments, proved a success, and a good supply of the parasite was secured after the ne- : . cqssary precautions had been .taken for the eliminiation of secondary parasites, OVERCOMING DIFFICULTIES. The rearing of the maggot fly para-, site was then undertaken in order that sufficient would be secured for distribution in New Zealand. At first considerable difficulties were met with .and the results were not satisfactory though small liberations were able to be made in the field during the summer bqfore Jast. it was, however, necessary to find sprue means of. rearing the parasite in large numbers, and after investigation a special technique was by which enormous numbers of the parasite could l be reared. This was during last - autumn and some large liberations were made before winter sqt in.

On taking up the position of c.hi'qf of the entomological department at the Cawthorn Institute in May last, and by arrangement between Dr. Mil-| ler ; and the Department of Agriculture the work of rearing and, establishing, the parasites was centred at the Cawthorn Institute.

From the over-wintering parasitised material transferred to the Cawthorn Institute there emerged this spring many thousands of parasites and extensive; distributions were made in the maggot fly areas of the Dominion. Part of the Cawthorn institute insectarjes has been set aside for the mass production of. the para-l sites, and now the; second brood spice winter is being distributed. These distributions will be made throughout the coming summer and autumn, when it is expec.ted that the parasite will be sufficiently established for practical purposes.

In the work of distributing th© parasites the director, of t'be Live Stock Division of the Department of Agriculture has, kindly consented to supplier being sent to the stock inspectors of the different districts; and the institute is especially indebted to the inspectors of stock at Blenheim (Mr, J. Gi Scott) and Nelson (Mr G. Rlair), for their vejry keen interest in this work. Right from the commencement of the enterprise Mr, C. G. Tesehemaker, of Avondale, has played a very active part, and hi's, station has beep really the field insec,taty where studies of the maggot fly posi-. tion and the establishment of the parasites in the Waihau basin, have taken place.