THE POTATO MOTH.

Otago Witness, Issue 2978, 12 April 1911, Page 19

THE POTATO MOTH.

(By Dr F. W. Hilgendoef.)

V'-'J *•' - • - ' The potato moth was fust found in Algeria, of which country it is probably a native. It is common in Australia, but is barely known in England. It occurs occasionally in the North Island of New Zealand, but the last outbreak in the South Island occurred in about 1894—that is, 17 years ago. The moth is brownish-grey, with fringed wings of about a iin span. It is a night flier. Mr Kirk shows that the moths pair within 24 hours of emerging from the chrysalis, and that the eggs are laid Within the next two to eight days. It is probable tbat (gs in tibe case of the diaihond black moth and the clothes moth) the mo ill does not food, or at any rate ran do without food and still lay its eggs-. The eggs are laid on the eyes of the potato or doubtfully upon the green, fresh haulms of the potato. The eggs hatch out into pinkish caterpillars with black heads, and the caterpillars average iin in length. They bore into the potatoes available and completely destroy them, foeccs of the insect inducing the growth of fungi which hasten the decay.. . , . , The above facts of the natural history of the insect indicate what lines of procedure will bo favourable and unfavourable to its attack. The potatoes lying on the surface of the ground will be found to be the only ones with grubs in them. If these are gathered with the dug potatoes and pitted, the grubs in the affected potatoes will produce moths, which will lay their eggs on the sound potatoes, and so cause the destruction of the whole pit, whose covering of straw and earth will provide a suitably warm shelter for the insect to breed under tar into winter. If the potatoes are dug now and left lying on the “■round overnight, or, as is usual, arc placed fn open bags with a heap of haulms thrown ever the mouth of the bag, then the moth will lay her eggs on the exposed potatoes (for she shelters in the haulms during the day time), and again there will follow destruction of the heap when pitted. If all the potatoes exposed above the surface of the ground are gathered and used at once for household purposes, and the bad cues fed to pigs (they are no- good for keeping if thov have the grub in them) then the remainder of the crop will bo sound. If the underground potatoes are then dug, picked up without delay, placed in sacks with closed mouths, and carted to sheds, Whoso doors and windows are closed, then

the moth will have had no opportunity to lay her eggs on them If the surface potatoes are gathered, and the well-buried ones left till the first frost, and then dug, they will again escape, and may be pitted with safety, for the moth belongs to warm climates and disappears with the first cold. As for a renewal of the attack next year, this is not very likely, since the moth has been in New Zealand 60 years and more, and only two severe outbreaks have been recorded from the South Island. Still, if anyone wishes to stave off a possible attack two plans suggest themselves. First, if all affected potatoes are destroyed this year there will be fewer moths for next; and, secondly, if next season's crop is well moulded up there will be no exposed potatoes for the moth to lay her eggs on. lb is, too late for moulding up this year.— C'hristehurch 'Press.