Notes on the Lord Howe Island Phasma, and on an associated Longicorn Beetle.

By Arthur M. Lea, F.E.S., Museum Entomologist.

[Contribution from the South A ustralian Museum.]

[Read June 8, 1916.]

Plates XI. - XVII.

One of the most remarkable species of insects that I obtained during a recent (December, 1915, and January, 1916) visit to Lord Howe Island, is a large wingless phasma, Karabidion (formerly Eurycantha) australe, Montr. It appears to have been taken by almost every natural history visitor to the island, and, in fact, once their hiding-places are known, specimens may be taken in practically unlimited numbers. During the day they remain concealed in hollows in upright or slightly-sloping stems of living trees, but their presence may be detected by examining the ground at the foot of the trees, where heaps of their excrement, sometimes amounting to bushels, may be found. The hollows are seldom less than eighteen inches in length, and are sometimes much longer; suitable ones are probably used for years. On examining the heaps of droppings, frequently both fresh and newly-hatched eggs may be found, the females apparently simply extruding their eggs as soon as these are ready.

Plate XI

Occasionally during daylight, when beating shrubs over an umbrella for insects, a newly-hatched larva, usually green, would drop into it; but except for these I never saw a specimen at large during daylight. They appear to come out late at night and to climb the trees directly for food. In the hollows considerable numbers live together in all stages, but with immature forms in the majority; from one hollow that was completely emptied sixty-eight specimens were taken; in the same hollow were several large spiders and cockroaches. The males are armed with formidable spines on the hind femora, and when being captured they attempt to use these in conjunction with the strong curved tibiae; the females simply try to escape.

Plate XII

The females vary comparatively little in structure, except that when mature the smallest is not quite four inches in length and the largest is a little over five inches. The males, however, vary considerably, especially in the hind legs; the smallest in the Museum measures nearly three inches, the

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largest about four and a half inches. The hind femora on the small males have armature not much more pronounced than on the females, but on the large males the two large teeth are very strong, and there are up to twelve smaller ones; the femur itself on the large males is considerably wider than the abdomen, and passes the sixth segment of the latter; whereas on the small males it is narrower than the abdomen, and may not extend to the tip of the fourth segment.

Plate XIII

Six specimens (all males) were taken, on which, a leg having been lost, it had been renewed; four of these were larvae, and the reviewed legs are very small (pl. xiii., figs 5-8). On the two mature specimens (pl. xiv.) the renewed leg is a hind one, and it is remarkable that with each the leg, in addition to being much smaller than the non-renewed one, is without conspicuous masculine armature approaching the female type.

Plate XIV

I saw no communities in dead trees, but was told that occasionally when a tree touched a house, and especially in the olden days when many houses were thatched, the phasmas would frequently take shelter in large numbers in the ceiling and make uncanny noises at night. But they were easily checked from doing this by preventing any part of the adjacent trees from touching the house. In nearly all cases that I examined it was seen plainly that the phasmas had selected for their domicile trees that had been largely bored by larvae of a large longicorn beetle.

(1) It is not Cnemoplites (Arimaspes) howei, as the late Mr. A. S. Olliff thought possible.

This beetle, Agrianome spinicollis, W. S. Macl.,⁽¹⁾ is abundant on the island, and numerous specimens may be taken at night on the trunks of many kinds of trees. The larvae make large borings and eject most of their excrement outside the trees; each makes a large hollow, and as many usually work together their borings frequently interlace; in time, with the work of other insects, timber-rotting fungi, etc., large hollows are formed, and in these the phasmas take up their residence. A large orange tree was practically destroyed by larvae of this beetle, and figures (pl. xvii.) are given of the inside and outside appearance of portion of the trunk of this tree, showing the great damage done. Large Kentia trees are also attacked. No living banyan trees were noticed to be attacked by it, but larvae were abundant in dead ones. Very old and rotten logs of many kinds of trees appeared to be attacked with as much favour as living trees, and their larvae are often taken from such logs by the islanders, with whom they are very favourite fish-bait.

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Both sexes of the matured beetles vary in length but the male may be readily distinguished from the female by its longer and stouter antennae and legs, especially the front tibiae and tarsi, pronotum with patches of coarse punctures alternated with more finely punctured and subopaque patches (instead of with coarse punctures throughout as on the female), and abdomen wider and subopaque, except that the fifth segment and tips of the others are shining; whereas on the female the abdomen is polished throughout.