CATERPILLARS

Evening Star, Issue 22004, 13 April 1935, Page 3

CATERPILLARS

(By J. Fleming, F.R.H.S., N.D.H. N.Z.)

At the present time throughout the North Island and as far south as Timaru in the South Island growers of the cabbage tribe are greatly concerned in combating the destructive pest called the white cabbage butterfly. It is interesting to know that this pest has been very prevalent in the Homeland for many years. Among the numerous caterpillars which attack the cabbage and allied crops the chief are those of the large white cabbage butterfly (Pieris brassicas), the small white cabbage butterfly (Pieris rapirc) mid the green-veined white butterfly. The first-named is the commonest and most destructive, but all are often present in the, same garden, and should be promptly dealt .with. The yellow eggs are laid on the underside of the leaves, and a smart person will detect and destroy whole colonies of them. The caterpillars are greenish in colour, spotted with black, more or less yellow stripe clown the back, more or less hairy, and generally have a welldefined yellow stripe down the back with other fainter stripes along thp_ sides. When fully fed they seek protection beneath the eaves of some shed or outbuilding, and turn to pale green, black spotted chrysalids. From these the butterfly comes out in about a fortnight in the first brood, but the autumn chrysalids do not open till the spring when the large butterfly, with large white, black tipped and spotted wings, may do seen flitting in the early sunbeams.

The other butterflies mentioned are very similar, but smaller. With regard to remedies, the first thing to do is to make a careful search for the chrysalids during the autumn and winter. Numbers of them can be found under the eaves of sheds or along the rafters inside sheds and outhouses. These should all be removed and burnt. The next step is to watch for the appearance of the butterflies, and catch them with a net. Next in order comes a hunt among the leaves for the eggs, and with the large white butterfly this is a paying practice. With tho other two it is, however, not so practicable, as they scatter their eggs over the leaves instead of laying them in a compact cluster. When the caterpillars appear, hand picking is the best means of effecting a clearance on a small scale. On largo areas dustings of fresh soot or finely powdered quicklime will be found useful, or salt may be used with much success A liquid spraying obtained from boiled lettuce plants _is found to be a good remedy by an industrious Chinaman in the North Island. High cultivation is also good, ns it enables, the plants to stand attacks upon their leaf area with impunity.