Art. XXVII.— Descriptions of the Larva and Pupa of Lasiorhynchus barbicornis.

Transactions and Proceedings of the Royal Society of New Zealand, Volume 13, 1880, Page 228

Art. XXVII.— Descriptions of the Larva and Pupa of Lasiorhynchus barbicornis. By Capt. T. Broun. [Read before the Auckland Institute, 21st June, 1880.] Larva. Colour: testaceous, more or less infuscate, head constantly castaneous, with piceous mandibles. Its form somewhat cylindrical, ordinarily compressed laterally, distended in front and behind. Composed of thirteen segments, the first forming the head, the penultimate and terminal with distinct dorsal sutures, but interrupted laterally and nearly obliterated below; all the segments with deep transverse furrows, their sides (except the anterior four and anal one) limited by a deep irregular groove, so that the rather flat inferior surface is very obviously separated from the sides. Head: much narrower than the second segment, sub-conical, rugulose in front, almost smooth behind, bearing several elongate fulvous bristles; epistome well marked, strongly transversal, its basal suture curved; labrum broader than long; mandibles robust, slightly notched at apex, uneven; eyes represented by small rounded elevations situated some little distance from the base of the jaws; maxillary palpi greatly developed, as long as the lower surface of the head, second articulation excessively short; third small, aciculate; the labial very small, connate, appearing to form the apical portion of the mentum; second joint small, cylindric, terminal needle-shaped; devoid of antennæ. The second segment broad, very finely rugose, with a large spiracle at each side, and a dorsal fold at its base; third broader than the preceding, broadly emarginate in front, with a large semicircular basal lobe, and a small chestnut-coloured elevation near each side; fourth equalling the former in width, obtusely rounded apically, its anterior portion separated from the basal by a deep transverse furrow; fifth to tenth with two dorsal grooves, the last-mentioned feebly impressed. The legs proceed from the second, third and fourth segments, are very short, and apparently only bi-articulate; they are setose. The spiracles, sixteen in number, are placed at the sides of the superior surface, on the second, fifth, sixth, seventh, eighth, ninth, tenth and eleventh segments. The whole surface is almost destitute of clothing, there being only a few scattered hair-like bristles, those on the underside shortest. The size is subject to considerable variation; the example before me, a small one, measures nine lines in length with both extremities incurved, and three in breadth, the middle parts, however, being much narrower. Pupa. Male measures nineteen lines in length, but with the rostrum projecting four lines beyond the last ventral segment. The head and rostrum attain a

length of twenty-three lines, are bent below the body, finely grooved superficially as far as the antennal insertion (not far from the apex), are without other distinct sculpture, though at uncertain intervals seeming slightly constricted; the antennæ repose at each side, extend forwards as far as the intermediate coxæ, in one specimen the external filmy covering has been removed, thus displaying the five terminal joints in perfection; the position of the eyes, identical with that of the imago, is clearly indicated by the lateral dilatation of the head. The prothorax is neither quite conical nor cylindrical but just intermediate in form, is armed at its apex with two pairs of horn-like, sometimes wrinkled, protuberances, two other but much smaller ones behind these, and two larger ones at its base; the front pair of legs attached thereto are obliquely folded below. The mesothorax is short, divided from the preceding by a deep frontal suture, is impressed with two longitudinal grooves; from it issue the elytra which lie obliquely along the sides, and the middle pair of legs. The metathorax is longer than the latter, very uneven, and bears the membranous wings and posterior legs; the tarsal claw envelopes of these latter reach the extremity of the body, and are perceptibly marked off from the covering of the tarsi. The abdomen consists of eight free segments, all of which, except the last, are distinctly separated from one another, the terminal ends with two large protuberances having a spine-like process at the extremity; their upper and lower surfaces are closely, finely, and irregularly wrinkled; the basal and two apical segments are more or less spiniferous above, the others are considerably raised behind, and on the summit of each elevation are placed eight short corneous, almost bi-articulate, spine-like processes forming a transverse row, whilst two or more less evident ones may be noticed on the depressed frontal portion. The female differs in several respects; the rostrum extends but little beyond the metasternum; the antennæ, inserted nearer the base than the middle of the beak, are directed forwards and then sideways, thus embracing the surface just behind the basal tubercles of the prothorax; it is only half the bulk of the other sex. Habits of the Insect. This paper would be held to be incomplete without some account of the habits of the insect. I shall not, however, inflict on the members of the Institute an elaborate series of details, which, indeed, could not be done without long and close observation under favourable conditions, but will content myself with the mere recital of facts, from which you may draw your own conclusions. The perfect female gnaws a hole but little broader than a pin's-head, and in the cavity deposits the eggs. If the tree or log be visited some

years afterwards, the following will be found to correspond with what usually occurs. On one occasion, when examining the forest north of Whangarei harbour, I noticed a karaka-tree which had been pierced by insects. I cut it down, and on opening it up found it tenanted by Lasiorhynchus barbicornis in all its stages. The larvæ were engaged in the formation of cylindrical drills running in different directions; the pupæ reposed in the attitude described above, i.e., with the head and rostrum (the two conjointly, it will be borne in mind, longer than the body itself) bent along the lower part of the body, in a hole just broad enough to contain the insect, and without external orifice to permit its subsequent egress. I also cut out a few perfect specimens of both sexes; sometimes these had so nearly effected their exit that the extremity of the beak protruded. Of course there can be no doubt that these beetles had themselves eaten their way through, but what filled me with wonder was, how the pupa, on arriving at maturity, had managed to straighten its rostrum so that the mandibles might be employed to effect its release? The description of the imago appears in my “Manual of the New Zealand Coleoptera.”* “Manual of the New Zealand Coleoptera” (Wellington, 1880), p. 543. Specimens are preserved in the Museum. I now add alcoholic examples of the larvæ and pupæ. With these before him, the student may proceed to the investigation of the question propounded, and if he can solve the problem without acknowledging the wonderful designs of the Almighty, he must be hard indeed to convince.