THE TURNIP FLY

Wairarapa Times-Age, 20 July 1938, Page 3

THE TURNIP FLY

DEFINED AS A BEETLE. PROBLEM OF CONTROL. In discussing “The Turnip Fly,” Dr A. E. Cameron, lecturer on agricultural and forest zoology in the University of Edinburgh, points out: — “In the first place the insect is not a fly but a beetle, and in the second place it attacks not only turnips but practically all cultivated cruciferous plants and a goodly number of wild ones as well. •< In recent years the insect has come to be known as the ‘lesser striped flea beetle,’ a name that serves to focus attention on two yellow stripes present on the back, contrasting sharply with the shiny black colour of the rest of the body and helping in the insect’s identification. As a true flea beetle the turnip fly displays those extraordinary powers of jumping for which flea beetles are justly notorious. “The remarkable feature of the life cycle of the turnip fly is the longevity of the adult insect, which lives for almost a year. , METHODS OF DESTRUCTION. “The attack on the crop may" commence even before the seedlings have pushed their way to the surface. To satisfy their hunger the beetles enter the crevices of the soil and nibble the tiny stem, causing irreparable damage to the small plants before they appear above ground. "Thus what often appears to be belated germination proves on examination to be failure due to turnip fly attack. Unfortunately, the damage does not stop here, but is continued upon other plants which have succeeded in bearing their seed-leaves to the surface. There now begins a concentrated attack on the seed leaves with the result that those plants which have escaped the earlier attack may succumb to the later one.

“In years of severe infestation farmers may have to sow twice or three times before the crop becomes established.” SOME USEFUL HINTS. To sum up, Dr Cameron emphasised the following facts:— There is only one generation of the turnip fly or flea beetle each year. The adult beetles first appear in August, and after hibernating in the soil and other suitable places re-appear in spring. The greatest damage is done by the beetles in May and June, when they destroy the seedlings. As a result re-sowing is sometimes necessary. (The foregoing are English times, of course). Since the seeding is most susceptible to damage, steps should be taken early to protect it. A fine tilth helps the seedlings to grow quickly, and rolling the land lightly when the seedlings are breaking through to the surface is also useful. The beetles are best controlled by the application of a derris or naptha-lene-silica dust. The first application is made just before the seedlings appear, and is followed by two or three further applications at intervals of four or five days.