
Art. XXXVI.—Description of the Larva of Pericoptus truncatus, with Observations as to Habitat.
[Read before the Auckland Institute, 2nd June, 1879.]
The larva of this beetle may be said to be of an elliptically cylindric form, being somewhat contracted near the middle, and with its first and anal segments, especially the former, narrower than the adjacent ones. Its upper surface is moderately convex transversely, the lower almost plane, but wrinkled. If preserved in its natural posture, the ventral segments may be seen to be considerably incurved, so that the hinder part of the body appears to be almost at right angles to the anterior. The lateral margins, though uneven, are well defined.
The body is moderately soft, but the head and claws are decidedly corneous.
The size varies according to the degree of maturity; my two specimens measure 17 lines in length by 7 1/2 in breadth, and 15 x 6 respectively, but if straightened, the larger must have about 14 lines added to its length.
Its colour is uncertain; usually a pale yellow or dirty white, but becoming more or less livid; the head, however, is constantly castaneous, with piceous mandibles, the claws also are pitchy, and the stout bristles borne by the legs and certain portions of the body are of about the same chestnut hue as the head. Sometimes the larva is irregularly spotted with blue, but the colour, as previously indicated, generally degenerates into a brownish white, with livid blotches.
The body is apparently divided into fourteen segments, all of which, except the first and three last, are strongly wrinkled transversely, so much so, that some care will be required in determining the difference between the real sutures and the folds; the three terminal are by far the largest; of

these the intermediate is the most bulky, though the apical is actually longer than it, and tapers somewhat towards the extremity. The head, including the mandibles, clypeus, and epistome, is more or less irregularly rugose, its sculpture, however, becoming finer towards the base, where there is an obvious longitudinal groove. The second and three terminal segments are almost glabrous, the intervening ones being more or less studded with short spiniform bristles, here and there intermingled with rather long hair-like bristles; these latter are also distributed over the surface of the other segments, the apex of the last, moreover, bears more and coarser spines than, are to be seen elsewhere. The under-surface bears many bristles, but is devoid of spines.
The maxillary palpi, including the basal articulation, are four-jointed, the joints are cylindrical, the terminal being the longest and slightly acuminate. The antennæ are more than twice the length of the palpi, formed of four distinct articulations, the socket not being reckoned; the true second joint is a good deal longer than the others, and, like the first, cylindrical, but obliquely cut away at the end; the third joint is so placed as to appear slightly forked, and is prolonged beyond the point of insertion of the apical joint, which, therefore, is quite furcate, and has two, more or less evident, indentations at each side. The clypeus is transversal, nearly truncate, and densely ciliated anteriorly. The eye is quite rudimentary, being represented by a small oval elevation close to the antennal orbit. The legs are rather long and robust, bent, coarsely hispid, and four-jointed, with an additional articulation terminating in a large, broad, horny claw: the second joint is short, and, doubtless, merges in the tibia of the perfect insect. The spiracles are situated at the sides of the second, fifth, sixth, seventh, eighth, ninth, tenth, eleventh, and twelfth segments.
In my second and smaller example, the under-side is roughly carinated longitudinally, and the terminal joint of one antenna seems as if cleft to its base. On examining the joint carefully, I notice that the inner side of one part is concave, and, consequently, adapted to receive the other. This peculiarity of structure, most likely accidentally exposed to view, indicates the presence of a rudimentary lamellated club, normally concealed by a more or less tough film instead of the usual larval joint.
This larva may be met with occasionally in the loose sand of the seabeach, under logs whose buried portion has become somewhat decomposed; but whether a certain stage of decay must have been reached before the larva resorts to the log, or the female for the deposition of the egg, I am, as yet, unable to state positively; this much, however, is certain, that the process of decomposition is greatly accelerated by the larva which gnaws into the wood itself. The masticated wood having passed through its

body, and accumulated around the cavity in the sand or debris usually occupied by the larva, would be apt to lead one to suppose, at first sight, that the wood must have been in a decayed state previous to the insects' recourse to it; experienced observers particularly might be deceived in this matter, knowing, as they do, that the larvæ of the Dynastidæ repair to decomposing vegetable matter as their natural food, their services being peculiarly valuable in rendering such substances innocuous. I apprehend that naturalists have still much to learn respecting the various modes of life of New Zealand insects; preconceived notions derived from the study of the habits of what may be termed “old-world animals,” would prove to be unreliable guides in the search for many of our species, which, to my knowledge, pass the various stages of their existence under circumstances quite at variance with cognate, or even congeneric, forms found elsewhere.
I am of opinion that decayed ligneous matter is not at all a necessary means of support to this species; if that were so, the larva would be more often seen; it is nowhere common, certainly not met with in such profusion as to account for the numbers of the imago that may on certain occasions be seen strewn, dead and mutilated, along the sea-shore. Its true home is, beyond doubt, the loose drift above high-water mark.
I have not been able to find the pupa, but I have frequently, especially on calm mornings, followed the tracks of the perfect insects along the beach, whereon they had been disporting during the night, and these invariably ceased amongst the looser drift-sand, into which, it must be evident, the beetles had burrowed, very deeply too, as I could never excavate a hole deep enough to reach them by hand. I was once fortunate enough to secure a living specimen, and, to place the matter beyond mere surmise, allowed him to escape from my hand, when he instantly sought refuge in the sand. At other times I noticed dead beetles belonging to this species which had not effectually secured their retreat, the hind-body being visible.
Another remarkable trait remains to be noticed, that is, the extraordinary paucity of female specimens; of the many hundreds of dead imagos I have seen lying on the beach at various times, I can only remember having found one female!! I do not mean to imply any analogy between the habits of Pericoptus and the Bee, beyond the touching fact of her domestic proclivities; if she were not a good wife or daughter, she would surely be more frequently visible to strangers.
I shall deposit an alcoholic specimen as a type of this larva in the Auckland Museum as soon as possible; the perfect insect is already there, and, when compared, they will afford a striking illustration of the metamorphoses of a beetle.
