WHITE BUTTERFLY

Evening Star, Issue 21080, 18 April 1932, Page 10

WHITE BUTTERFLY

WELL ESTABLISHES YET AJiOTlicß PEST The while butterfly—tho English " cabbage white." as it is sometimes called—jrsas now apparently lairty welt spread itself over New Zealand. It made its lirst appearance in Hawke's Bay about two years ago, and then was observed in various other localities. A low months ago (says the ‘Post’) specimens were reported as having been seen around Wellington, and within tho last few weeks it has been reported as having reached South Canterbury. There is little doubt, therefore, that by next year tho buttorlly is likely to be well 'established throughout tho. dominion. Whence it came it is too late to worry about now, but it is supposed to have come from Hawaii in some imported fruit. Tho main point is the pest is here, and here it is -likely to stay in company with many another which lias been ’ imported, accidentally or otherwise. What concerns New Zealanders is how it is to bo kept in check. There is no mistaking tho white butterfly, for it is totally unlike any butterfly which is native to Now Zealand, it is almost pure white in colour, but on the wings are very distinct black to greyish markings which give it a somewhat smoked appearance. In England and Europe there are three distinct varieties, all similar in appearance, but varying in size. Tho variety that has taken up its residence in the dominion measures up to a couple of indies Iron) wing tip to wing tip—quite a fair size as butterflies go. It is a great lover of the sunshine, and in England it is looked upon as a fairly reliable weather indicator. The plentiful sunshine in Now Zealand should therefore suit it down to tho ground, in England it is exceedingly plentiful, and, in company with tho less common “ garden yellow,” can bo seen in hundreds on any sunny day in spring and summer. The fear now is that in New Zealand it will be seen in thousands and millions if not checked. VORACIOUS CATERPILLARS. Unfortunately the .esthetic value of the white butterfly flitting about tho garden is more mail offset by its economic destructiveness. Not that the butterfly itself is destructive. During its short life it sips a little honey, but it also lays eggs (if it is a lady), and those eggs hatch out into fair-sized green caterpillars, which seem to have an unlimited appetite. As an example, twothirds of a crop of swedes, covering an area of over fifty acres, have been eaten in one week by these voracious caterpillars. Although called the “ cabbage ” white, the caterpillar of this butterfly does not confine its attention solely to leaves of cabbages and allied plants, although it apparently prefers these as u diet when it can get them. Crops of rape, kale, turnips, swedes, and the like will be attacked, and so will many other things in the garden. For instance, one of these butterflies during the summer of this year managed to lay its eggs in a Lower Hutt garden. It selected some marigold (calendula) plants as a nursery, and when the caterpillars emerged they made exceedingly short work of every available leaf. WASP SMALL AND HARMLESS. Needless alarm has been expressed in some quarters about the introduction of parasitical wasps to, combat the white butterfly, it being erroneously thought that the wasp in question is the ordinary stinging wasp so common in England, Tho question was raised in the House, and the Minister of Agriculture (Hon. C. E. Macmillan) made it quite clear that while the parasites it was intended to utilise for destroying the white butterfly belonged to the wasp family, they were quite different from the ordinary wasp. These parasites were very minute insects, which laid eggs only on tho larvae of the butterfly. They possessed no stings and consumed no food during the period they were on the wing, and during all other stages of their lives fed only on the larvae of the butterflies. QUESTION OF CONTROL. As far as control is concerned tho question has been asked: Why worry? The butterfly Jin’s been in existence in England and elsewhere for hundreds of years; it may bo , a nuisance, but is hardly a pest about which to get frantic. This, however, is false reasoning. In the older countries a natural balance has been struck between pest and parasites, and this also has been established for hundreds of years, the pest seldom being allowed by Nature to get out of hand, so to speak, although-thr.c are years in which its ravages are worse than in others. Hut put a pest like tho white butterfly in a new environment like tiio dominion, and there is nc natural balance; the butteifly has it all its own way. The small parasitical wasp with which it is proposed to combat the white butterfly can at best cheek its abhocmal increase; it is very unlikely to wipe it out. In England arsenical sprays have been found effective in control measures bur to apply this method to large areas is impossible. One can but hope that the white butterfly wiM not find New Zealand such a congenial country in which to live as it is made out tc be. that some natural enemy will arise and deal effectively with it. Rut that is a forlorn hope, and prcmmably New Zealanders wilt have to add the white butterfly to the. already long list of imported post;;, .such as blackberry, gore. ragwort, rabbits, and earwigs, to mention only a few.