BLOWFLY PEST

Hokitika Guardian, 12 May 1930, Page 8

BLOWFLY PEST

RA FAGES AMONG SHEEP

FARASI'jiE MAY, BRING' RELIEF

Marked success has attended the efforts of the Caythorn, Institute, Nelson, to. introduce a" parasite'to combat the blowfly, one of .the worst enemies of the sheepfarmer. Canterbury farmers contributed money to the msearen and many of them have had/supplies of the parasite from the institute, and have thus; been able to judge df its work for themselves, j .

Mr A. F. Clarke, forest entomologist to the Cawthorn Institute, explained yesterday that the parasite was a Braconid and a native of England whence they had imported it. It worked in a curious way. When liberated it attached itself to the lava op grub of the fly, which had been laid on the sheep. Here the parasite laid an egg itself. Shortly after the grub of the blowfly pupated and the parasite egg, hatching out, fed on the developing blowfly. Then, instead of the blowfly emerging from the pupa,, the adult parasite emerged.

There had been some doubt, said Mr Clark, about the parasite acclimatising itself in New Zealand, but actual obser. varfions in the field in Canterbury itself had proved that it had bred here and was likely to become acclimatised at a rapid date. EFFECT ON BLOWFLIES.

“Are blowflies to become extinct then when this parasite marshals its force?” queried the reporter. “They will become less,” replied Mr Clark, “but it is improbable that they will be exterminated. You see, the parasite has to find the grubs of the fly before he can begin his war upon tu'iem. It is not likely that the parasite will ever destroy all the larvae of the fly; it is difficult to say how much it will decrease their number, but it vbpuld reduce the fly’s ravages among ’•cep materially. It has been successful in England, and so long as acclimatisation is successful it should sue ceed here. There are five or six different species of blowfly but the Braconid does not discriminate.” SPECIALISED DIET. The reporter enquired if there was a danger of the parasite becoming, in ■me, the pest. There was none, said Mr Clark, and for a very interesting reason. The parasite hatched and grew within the body of the grub of the blowfly, feeding on the grub the while. Put if there were no blowflies it would <"o hard with the parasite. Its diet was so specialised that it could live only on blowflies; without them it would starve.