SANDFLIES

Hokitika Guardian, 21 June 1930, Page 6

SANDFLIES

BREEDING GOUNDS FOUND

AN INTERESTING DISCOVERY

A discovery Avhieh may go a long Avay towards controlling the sandfly pest in Ncav Zealand was made by Professor E. Fercival, of Canterbury College, during ms rcent tour of the southern Lakes.

Professor Fercival found the upper reaches of the AVaiau river, which drains three lakes, rich in animal and vegetable life. Closer inspection of the bed revealed something which appeared like a slimy growth on the bottom of the stones. These proved to be the eggs of sandflies. ‘'■‘'There 1 'were myriads of them,” said the Professor. “Of . course it had been known for a long time where sandflies breed, hut .1 don’t think anyone in New Zealand has come across such an onormjous number of their eggs as I suav. Over hundreds of square yards fair-sized stones on the hod of the river Avere ooated .on their under-surface with these eggs.” '

The professor considers this a very interesting scientific discovery with practical value, for it means that any attempt to control the sandfly may be directed toAvards their breeding places.

HABITS OK SANDFLY,

He explained that the control of the sandfly Avas' much• more difficult tiian Avas generally assumed—more difficult than the control of the mosquito. In New Zealand there Avere six or seven different kinds of sandflies, nil belonging to the same genus, 'their bite avus not poisonous hut very irritating, especially in the lakes district where he had: made his discovery, and in the neighbourhood- of Alii ford Sound, lie had been told that a man could not. hear the torture from them in the bush in the summertime.

The sandfly always laid its eggs in running Avater Avhereas the mosquito generally chose . stagnant pools. There were three stages in. its life, the egg. tne griib, and. the .fly. The egg Avas laid usually on tne bottom of stones m a stream and av,lien it. hatched into the grub this also, clung to the stone, Avliich took its food .from the Avater as the current swayed, it .to and fro. When it blossomed into the chrysalis stage it floated t o tne surface of the Avqter and from the,, cocoon the fly made its exit. The life of sandflies had not been ascertained, but .they probably lived lor a Ateek or „ ... The process of hat’cliing arid developing. Avas accelerated by warn Avater: hence they ' .bred'much more quickly in summer ' tiffin' in winter. It was hardly necessary to say that they Avere also much more' voracious in warm AA'eatlier than in cold. - '

METHODS OF CONTROL

Speaking of control . Professor. Pereira! said thajt the ’ meltlijocls. used against mosquito -av.qu,ld'l not succeed against the sandfly. TJio practice of pouring kerosene on the surface of the Avater ivoukl not do because the kerosene avoulcl not stay. A small fish, some of Avliich AA'ere being imported into Ncav Zealand, Avas found to be fairly effective against the mosquito, blit these would not account for many of the sandflies.

The difficulty a - as that sandflies bred in all kinds of places, some of which Avere not accessible and cascades to be found in the mountain country might Avell act as breeding grounds for them, : and it Avas difficult to control them in. all these various places. “Where running water is, there also mac !:<. (guild, the sandfly,” said the Profo'.sor. ■, • ; ■

Lut if it .was found that they bred in colonies libs the, large one he had f'ohi d. !Tss sometning might he done to destroy Tiem there.

DRAGON ELY

Mr A. L. Tonnoir, of the staff of Hie Cawthron Institute, Kelson, had made ndflSi.es and their habits a subjects of- research. Ho had found that where a certain species of dragon Hy was common they destroyed the larvae of sandflies. This fly, a native of Australia, was being imported into flew Zealand but the Professor was doubtful if it would be equal to the task of combating the sandfly. For one thing ho did not belive that it would spread quickly to all the diffeient places frequented by the sandfly