At first sight, one might well be pardoned for considering a “vegetable caterpillar” as a specimen of the “mermaid class,” cleverly constructed by some ingenious hand, in the same way as the naturalist Waterton prepared his “nondescripts” for his museum; but, more closely examined, Nature triumphs, and not only so, but by the variety of ways in which she effects the same end, illustrates anew the axiom that no two things are exactly similar. For a long time I thought that there was but one simple form, all the specimens that came under my notice, either in England or in this colony, being the more or less desiccated caterpillar, bearing on its head a spike a few inches long, covered near the apex with spore capsules.

A short time since, I visited a part of the bush near Tarawera, on the Napier–Taupo Road, and very carefully searched over a considerable portion of high, bush-covered ranges, near the township, for a rare and interesting plant which I had previously obtained in that locality; and in the course of my day's ramble, I collected the specimens which I have the honour to lay before you this evening.

Taking one of the largest of the specimens, we find that the length of the caterpillar is about 2 ¾ or 3 inches, and the smallest 1 ¾–2 inches.

The largest caterpillar supported a fungus about 12 inches in length, 2 ½ inches of this being covered with densely packed spores. The number of specimens collected on this occasion was 16, 10 of which were mature, having the spore capsules fully developed, and six were immature. Three of the caterpillars were markedly smaller than the remainder, but, as far as could be seen, presented no specific differences. In all of the smaller specimens, however, the frontal shield, or scutellum (if any), was destroyed by the growth of the fungus.

Three of the caterpillars bore, what was then quite new to me, two or more spikes. The most remarkable of the three was a caterpillar 2 ½ inches long, bearing a stout fungoid spike, which ascended for 1 ½ inches, and then bifurcated, each branch being 9 inches in length, both being covered with spores for about 3 inches from the point. The second bore two spikes, each 6 inches long, both arising from the point of junction with the body, and both fertile. The third bore a many-branched spike, having nine points.

In the large majority of instances, the vegetable growth is seen to have arisen from the centre of the junction of the head and the scutellum, but in others, from either the right or left lobe of the head. In one case it occurs at the side of the first thoracic segment, and quite recently I have received from Major Scannell, of Taupo, a caterpillar bearing a spike at each end of the body; this being but the second time he has seen such a case occur, out of many hundreds of specimens.

The line of growth is, in all my specimens, coincident with the length of the body of the caterpillar, so that, if the caterpillar be placed in a crawling position, the “bulrush” extends in front of it like the bowsprit of a vessel. This is quite different to any of the engravings that I have seen in various books. Uusually the spike is represented as growing at right angles to the body, and the caterpillar is gaily crawling on the ground, bearing the spike, whilst what is presumed to be the perfect insect flies away in the distance. And now to return to my own specimens. All that I obtained I found buried in the ground in the dense bush, with but a very small proportion of what I have called “the spike” visible, and considerable care is required to dig out a specimen without breaking it, especially the finer ones.

In an article recently published in a Southern paper giving a lively account of this vegetable caterpillar, the statement is reiterated, which is found in all books on New Zealand, that the Aweto, or vegetable caterpillar, is only found under the rata tree (Metrosideros). Now, in the part of the bush from which my specimens came, there is no rata, and to find specimens it is best to look under the papa-namu (Coprosma grandifolia).

No trees can be more unlike than the Metrosideros and the Coprosma, and yet the larvæ probably feed on the leaves of either tree. It is possible that the differences perceptible in the caterpillars in the dried state might be more easily examined and determined when in the living and perfect state, but I have not yet had any opportunity of examining living specimens.

I believe vegetable caterpillars have been found in nearly all the forest districts of New Zealand. I have seen them from the Seventy-mile Bush (the Puketoi Ranges), Te Aute, Te Haroto, and Tarawera in this neighbourhood, and from various parts of the Wellington Provincial District.

And now let us examine a specimen a little more closely, and compare it with similar instances from other countries. On making a transverse section across the sporiferous portion, a closely-packed ring of conidia or spore-cases is seen arranged round a woody axis, the structure of which is not well-defined. The spore-cases, under the microscope, appear like grapes of a rich brown colour, and some appear to show a light spot near the outer end of the longer axis, through which probably the sporidia are discharged. Intermixed with the spore-cases occur numbers of what are probably linear sporidia, slightly twisted and jointed; sometimes these occur in tufts. In the “Handbook of the New Zealand Flora,” the caterpillar-fungus is placed under Cordiceps, but in more recent works on fungology it appears as Torrubia, owing to the discovery by Tulasne of secondary forms of fruit.

Why this fungus should attack this particular species of caterpillar is at present a mystery. Kindred forms are found generally distributed over the world. Perhaps even more striking than our endemic species is La Guěpe Végétale, or vegetable wasp of the West Indies. In this case the wasp has been observed flying about with part of its body filled up with the mycelium of the partly-developed fungus (F. sphæcocephala).

In this case it is beyond doubt that the insect dies from the growth of the fungus, and that the fungus is not the subsequent intruder, as has been suggested in the case of our caterpillar. Another case in point, in which the fungoid growth certainly causes the death of the host, is the silkworm disease (muscardine). In all cases which have come under my notice the whole of the body of the caterpillar has been filled with the mycelium of the fungus, and nearly all traces of the internal structure obliterated.

It is well known that many of the larvæ of the larger moths hybernate for indefinite periods, and take a considerable time in coming to the pupa state. It may be that, during the dormant period of hybernation, the sporidia may work down the burrow of the insect and germinate, ultimately reducing the animal to the state in which we find it. It seems natural that a caterpillar when hybernating should remain with its head to the surface, ready to emerge when better times come round; and this would account for the general position of the fungus, quite as well as the theory that the spores become fixed in the interstices between the segments whilst the animal is entering the ground.

About twenty-five species of this genus of sphæriaceous fungi have been described in South Carolina; one in Pennsylvania, on a beetle, and one on a moth; one in Cayenne, two in Brazil (one on an ant), two in the West Indies, one in New Guinea, and one in Senegal. In Australia two species have been recorded. Dr. Hooker found two in India, in the Khassya Hills; three have been found in Great Britain, and one has been found in China, where it bears a great repute as a medicine, to be administered as stuffing to roast duck.

The genus Cordiceps (Fries), in the “Handbook of the New Zealand Flora,” contains two species: C. robertsii (Berk.), and C. sinclairii (“Hbk. N.Z. Fl.” p. 338). The second species is totally different in general appearance, and attacks the larvæ of one of the Cicadæ, or Singing Locust. Every year four or five of these vegetable-locust grubs are found in digging over a small patch of garden ground in the Petane Valley. I regret that I have not had time to examine these specimens closely, and consequently cannot offer any further remarks on them. I also regret that I am unable to lay before you the moth (Hepialus virescens?) into which, if unmolested by the fungus, the caterpillar is said to develope. Any resident in the neighbourhood of any locality where vegetable caterpillars are found, might