Art. XII.—On the Habits of Dermestes vulpinus.
[Read before the Auckland Institute, 20th June, 1898.]
This is a very destructive beetle which I have had under observation for the last three years, having first noticed its larvæ in a building in Whangarei in December, 1895. Since then I have carefully noted its metamorphoses each season. This insect has been imported here, very likely in bones from Sydney. It is placed amongst occasional agricultural pests in England and America on account of its ravages—which are well known—on skins and hides. It is unnecessary to enter on these here; but its injuries to bones and wood seem much less known, and therefore a few remarks may be of interest.
The average size is about ⅜ in. long. The shape is somewhat narrow and flattened. The general colour above brownish or greyish-black, with more or less very short pale fine hairs, and white pubescence on the head; a broad band along each side of the thorax or fore-body being much more thickly covered with longer and whiter hairs, so as to show clearly, like a long white or grey patch; beneath the abdomen quite white.
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The beetle, I believe, will propagate on grease, or dirt of that nature, but only in very hot weather. The larvæ are very hairy, and in length average over ½ in., and when about to change to the pupa state will burrow into the sound woodwork of a building, which in some cases is reduced to a honeycomb. The largest specimens noticed by me were a little over 5/8 in. long by 3/16 in. in diameter, subcylindrical, tapering gradually to the tail, more bluntly to the head; general appearance brown above, whitish below, excepting towards the hinder extremity, where the brown colour turns down, as it were, from the upper side, and extends beneath to the tail; a pale yellowish-brown line runs along the centre of the back above, and between each segment there is usually a yellowish line. Above the tail, which is bluntly pointed, are two somewhat thorn-like processes. Head dark-brownish, as also the six clawed legs.
The eggs are hatched in from four to seven days, and the newly hatched grubs, which at first were almost white, in a few hours took the ordinary colouring, and buried themselves in their food. After moulting several times, the full-grown grub formed a chamber in its food material, or in any other convenient locality at hand, when it curled itself up, loosely
covered with some of its own food and the refuse around it. There it lay for five days, then moulted again for the last time, and turned to the pupa (or chrysalis), from which the beetle developed in thirteen days.
The temperature I kept was about 70 deg.