THE PURIRI MOTH.

Taranaki Daily News, 19 October 1921, Page 8

THE PURIRI MOTH.

SOME INTERESTING OBSERVATIONS. Mr. W. W. Smith, the well known naturalist, writes to the editor as follows: — Several readers of the News have posted to me copies of your issue of Friday, 14th inst., containing some interesting notes on a swarm of this magnificent moth at Kaponga during an evening last week. The larva of this large insect is the well known puriri borer that destroys much of the valuable walnut-like timber of the puriri, and that of other native trees, thus rendering them unfit for the finer work of the cabinet-makers. The causes of the irruption of swarms of some species of insects anti birds into distant parts of a country from their usual haunts, and, I may add, of sea-fish into distant parts of the ocean, after varying periods of years, are of great interest to naturalists, but are not in all cases fully understood. Swarms of the puriri moth (Hepialus virescens) have appeared at intervals of years since the settlement of the Taranaki province. The late Mr. W. L. Newman, informed me three years ago that when a boy fifty years ago, he remembered a season

in which, for several evenings, immense , numbers flew in at the windows of many houses in town, and extinguished the lamps. It is seven years since these fine moths were so numerous as they are at the present time. Unfortunately they are not likely to decrease in numbers, as the larvae now attack and bore and destroy the stems and limbs of many species of valuable introduced economic timber trees. The ash, beech, birch, elm, laurel, oak. and Indian strawberry tree may be cited as perfect illustrations locally. In addition to the puriri, fourteen other species of native trees are known to be attacked by this destructive borer. This largo and beautiful native moth was first described by Henry Doubleday, an English entomologist, in 1848. Though it has been known for over 70 years, its full life-history, or cycle of existence. is imperfectly known. After being laid by the moth in the crevices of the bark of trees which the larvae bore, the eggs are hatched in from 12 to IS days. How long the larvae bores in the tre’e attacked before transforming to the pupa or chrysalis state is unknown. I have known larvae to remain working in their tunnels for from 21 to oyer 3 years. The perfect or winged insect is extremely variable in its coloration. The moths range in color from many shades of oreen to shades of yellow, and shades of pink with white venation. Whether or no the trees in which they bore impart the varied coloration is not known. When a freshly emerged female is immediately placed in a box, and kept confined for a few days, it will lay two hundred or more eggs. The morepork owl and domestic cats consume the moth when numerous in laro-e numbers. When mounted on proper’pins and placed in an insect cabinet the moths soon lose their coloration, and the body is soon destroyed by a species of mite' which is very common in this district.