Art. XLIX.—On Entomological Field-work in New Zealand.
[Presidential Address to the Wellington Philosophical Society, delivered 19th June, 1900.]
In accordance with the established custom, the task of delivering an inaugural address devolves on me this evening, and I trust that members will excuse the comparatively limited scope of the subject which I have selected for my address. I feel, however, that any essay on general science that I could compile would not be at all adequate for the occasion, more especially when contrasted with those extremely able contributions of a general nature which have been already given to us by several of my predecessors in office.
With your permission, I therefore propose to occupy your attention for a brief interval this evening by some remarks on matters of general interest in connection with entomological field-work in New Zealand, and shall dwell especially on those methods of investigation which are likely, in my opinion, to be the most conducive to the advancement of science in the future. In fact, I intend to emphasize what has to be done, rather than what has been already done, as by this means I hope to stimulate and encourage our rising naturalists to direct their energies into useful channels.
In any country where the insect fauna is incompletely known it may be safely said that the first and most important step to be taken by the naturalist is the formation of good and exhaustive collections of specimens. This is especially the case in New Zealand, where the progress of settlement and the introduction of dominant forms of life are producing the most rapid and far-reaching changes in the original inhabitants, both animal and vegetal. Dr. Sharp, in an address delivered before the Entomological Society of London some years ago, drew special attention to the need for the immediate formation of collections of insects, especially in those parts of the world undergoing rapid changes through the agencies of civilisation. He also mentioned that the felling of forests in islands inflicts a fearful loss on the naturalist. As he points
out, the available collecting-power of a community is very small, and we should therefore husband our resources—that is, we should concentrate our efforts on those spots where species are most likely to suffer extinction. These conditions may be said to apply to New Zealand species generally, but more especially, I think, to those species which frequent the native forests, particularly in the North Island.
Hence I consider that forest collecting is at present one of the most important branches of field-work that New Zealand entomologists can take up. This being the case, I shall begin my remarks to-night with a few notes on the collection of entomological specimens in our New Zealand forests.
The best months for forest collecting in the lowlands of New Zealand (meaning by lowlands localities not exceeding 1,500 ft. above the sea-level) are November, December, and January, December being really the best of all. At this season a very large proportion of our known Lepidoptera may be obtained in a favourable locality, as well as large numbers of species belonging to the lesser-known orders of insects. The Coleoptera are also extremely abundant during the early summer, and a great many species may be found by beating the foliage or blossoms of trees over a sheet spread on the ground, or, if the ground be too rough for this, into an inverted umbrella, preferably a large, one, lined with some white material. By similar methods a good collection of spiders may also be secured.
I have found that forest ravines or river valleys are much more productive in insects than hill-bush far removed from water. To work a forest fully, it is necessary for the collector to follow up the stream and thoroughly beat the foliage on each side. The insects are then captured with the net as they fly out. To do this successfully requires a sharp eye and quick hand, as a lengthy pursuit is almost always impossible in such situations. If the stream is a fairly small one, wading may often be resorted to with advantage; and, in fact, it is very seldom feasible to work a forest stream efficiently without taking to the water occasionally. Many interesting species of Lepidoptera, Neuroptera, and Diptera (the latter mostly Tipulidæ), frequent the overhanging banks of deep forest ravines, and can only be dislodged by a vigorous probing with the stick into all the nooks and crannies. A dried manuka stick, fairly stout and about 5 ft. long, is very suitable for all this class of work, as well as being a most efficient aid in climbing over boulders, logs, &c., which always more or less obstruct the passage of these streams. The same class of stick is also most suitable for mountain work; in fact, the entomologist almost always requires a long stick in one hand and the net in the other.
The black-birch (or beech) forests, which are so common on high ranges, are comparatively poor in insects, though they sometimes yield species not found elsewhere. This is well exemplified on the Dun Mountain, near Nelson, which is, in fact, the only locality where I have taken the curious little black moth (Dicromodes nigra) exhibited this evening.
One very interesting feature connected with our forest dwelling moths is their extreme variability and their very wide geographical range, so far as New Zealand is concerned. I have much pleasure in exhibiting a number of specimens illustrating both these points. Each of the species of insects selected will be seen to vary very much within the limits of the species, and all those represented have been taken at various localities from Wellington southwards as far as Invercargill, and Stewart Island. Unfortunately, but little collecting of Lepidoptera has at present been done in the north, but Captain Broun has investigated the beetles of that region with indomitable energy, as his volumes of published descriptions of additional species abundantly testify. Some experts in the study of the Coleoptera consider, I believe, that a very substantial reduction in the number of species described by the learned captain will ultimately prove necessary; but, be this as it may, the name of Broun will in the future undoubtedly be associated with a very great number of species of New Zealand beetles.
Many forest-dwelling Lepidoptera are green, and these comprise some of our most beautiful species, their colouring imitating most faithfully the delicate hues of the beautiful moss-covered logs so common in our forests. These species are, unfortunately, extremely difficult to adequately, preserve, owing to a tendency almost all these green moths have to fade after death to yellow or dull brown. They should never be exposed to the fumes of cyanide of potassium or laurel leaves, two common killing agents used by entomologists, but should always be killed by means of the fumes of chloroform very sparingly applied. The specimens should be set immediately they are dead, and dried as rapidly as possible. If these precautions are adopted the beautiful green colouring of the living insect can, to a great extent, be preserved.
The destruction of the forests in the vicinity of Wellington is, of course, a trite subject to every one, and many members can no doubt remember far greater changes in this respect than I can. I may instance, however, as a probable result of this destruction, the striking decadence in the number of two common insects which has taken place within my experience of some eighteen years only. During the summer of 1882–83, which was the first season that I collected insects at Karori, I remember that at evening dusk the air was literally swarm-
ing with specimens of Hydriomena deltoidata. These moths were so abundant that four or five specimens would fly out of a single bush, and frequently two or three specimens would be captured in the net at once. In fact, the abundance of this particular species was most embarrassing to the collector, as it was liable to be mistaken for many rarer, though somewhat similar, species. Last summer (1899–1900) I certainly did not see more than a dozen specimens of H. deltoidata, and it cannot now be called a really abundant species. I have noticed the insect steadily declining in numbers during the whole of my entomological experience in the neighbourhood of Wellington, and I am inclined to attribute it partly to the increase in the number of sparrows, and partly to the denudation of the forests, for, although I have only found the larva of this insect feeding on a species of Plantago, I am inclined to think that it also probably feeds on some of our native ferns. The moth used to be most abundant amongst luxurious patches of ferns in rather open spots in the forest, and it is still common in such localities, when these are situated far away from settlement.
Another species that has declined equally in numbers during the same period is Somatochlora smithii. During the past three years I have been specially anxious to obtain many examples of this, and, in fact, of all our native dragon flies, and its comparative rarity has consequently been somewhat forcibly brought under my notice. In 1883, I remember, this insect was abundant over every stream in Karori, and at that time I used to frequently observe the females depositing their eggs in the water, the long abdomen being beaten violently on the surface during the process. Now, however, it would be quite impossible to make any such observation. In fact, during the whole of the past summer I saw only two specimens at Karori, and these seemed to have come from a distance, as they were frying very high in the air, apparently migrating. The larva of this insect lives in the mud at the bottom of stagnant streams and ponds, and may, perhaps, have been destroyed by the ever-increasing number of trout, otherwise it is difficult to understand what causes can have led to the great decrease which has taken place in the numbers of the perfect dragon-fly. Introduced insectivorous birds, through feeding on the imago, may, again, be suggested as a cause of decadence; yet the insect is an extremely rapid flier, and should be able to avoid capture to a great extent. However, the fact of a great decrease in the number of specimens of S. smithii in this district is certain, whatever may be the cause to which we may attribute it.
A great number of the forest-dwelling species in New Zealand are nocturnal in their habits. These can only be
captured by searching the flowers and foliage of shrubs and trees by the aid of a powerful lantern at night. Of all the methods of night collecting in New Zealand the examination of blossoms stands first, and amongst these the flowers of the white rata (Metrosideros scandens) are probably the most productive in insect life. One very handsome moth, Gonophylla nelsonaria, of which I exhibit a series, has been taken on these blossoms at night only, and although I have made the most careful searches during the day-time in the localities where the insect has been common, I have never succeeded in finding a single specimen. The flowers of the various species of Veronica are also very productive, and Mr. Howes informs me that the blossoms of the common ragwort, which grows so abundantly around Invercargill, is a most attractive flower to nocturnal Lepidoptera in that locality.
I have noticed that the various species of tree-ferns are extremely productive in moths, and large numbers may frequently be dislodged by beating the dead fronds, of which there is often a great accumulation in undisturbed portions of the forest. A sharp kick with the heel of the boot on the stem of the tree-fern is also a very efficient method of dislodging the various insects which lurk amongst the living fronds. The rough stems of these beautiful plants also form resting-places for many interesting species, notably Porinaenysii, an insect I have seldom met with except in this situation. It is, however, extremely difficult to detect it when resting closely concealed amongst the nodes of the fronds.
Another good method of working for forest species is by means of a careful scrutiny of tree-trunks. This work is sometimes rather tedious, owing to the great difficulty that the unpractised eye at first experiences in detecting insects, which are specially protectively coloured for concealment in such situations; but the results ultimately attained by tree-trunk searching are often extremely satisfactory. The knowledge of the different classes of protective colouring, and of the innumerable protective adaptations and instincts, which is naturally acquired by the entomologist during a careful scrutiny of tree-trunks, is of great scientific value, quite apart from the capture of many interesting specimens. In fact, it may be safely said that the searching for insects in their natural surroundings has led to the perception of some of the most advanced scientific truths with which we are acquainted. I refer more especially to the discovery of the different classes of colouring, structure, and instincts which have been acquired by insects for protective and aggressive purposes through the agency of natural selection. The uses of these peculiarities of colour, &c., could only be accurately interpreted by a more or less complete know-
ledge of the creatures’ natural surroundings, and this knowledge can only be obtained by those lengthy observations in the field which are usually made by the naturalist whilst he is engaged in collecting and searching out rare species in their natural habitats.
That moths and other nocturnal insects are attracted by light is a fact familiar to most people, but the experienced collector desires to turn this habit to good account. To do this effectively much depends on the surroundings of the collector's residence, and if his house happens to have a window facing an extensive area of virgin forest or swamp valuable results may be reasonably anticipated. If practicable a powerful lamp should be exhibited immediately outside the window of the collecting-room, as this has a very extensive range, and another lamp placed on a table just inside the window. The usual accessories—net, bottle, pins, &c—should, of course, be easily available. With regard to the most suitable times for lighting up, I cannot do better than quote from the late Mr. Stainton:—
“Next, two particular points have to be borne in mind— First, you cannot collect by light on bright moonlight nights; you must notice when the moon rises and sets, and light up accordingly. Second, you cannot collect by light if your window faces the wind, for moths fly against the wind, and if the wind is west you must put your light on the east side of the house, or if the wind is east you must have your attracting-room on the west side of the house. Moths begin to come to light as soon as it gets dark, and continue coming for some time—indeed, occasional stragglers will come throughout the night; the collector might therefore, with advantage, remain in his collecting-room till daybreak, ready to secure every specimen the moment it appeared, for some only remain for a short time in the vicinity of the light and then fly away, and others, which remain quietly enough half the night, fly away before daybreak. However, if the collector does not wish to sacrifice his whole night's rest at the shrine of science, let him go to bed about midnight, and let him revisit his collecting-room an hour or two before daybreak to secure any specimens which have come in during the night. On some nights moths come veritably in troops to the light—Bombyces, Noctuæ, Geometræ, Pyrales, Tortrices, Tineæ, and Pterophori—it is a mad race which shall come in; but these gala nights are very scarce—sometimes there will not be above three such nights in a year. And here is shown the necessity for the collector, who wishes to attract insects by light, to attend systematically, for the good nights cannot be distinguished by our senses from the bad ones, and if he only lights up now and then, instead of regularly, he will be almost sure to miss the
good nights. I once knew a continuous fortnight of good nights. When the small Psychodæ come in great numbers, so as to blacken the windows and ceiling of the collecting room, it is almost an infallible sign that the moths are coming in numbers.”
The open lowlands in New Zealand are not nearly so productive in insect life as the forests. The original flora of these localities is, however, undergoing rapid alteration, owing to the extension of settlement, though the changes are not so great as in those places where the complete clearing of extensive forests is proceeding. The tussock-covered plains in many parts of the South Island remain practically in their primitive condition, though the periodical burning of the native grasses must destroy immense numbers of insects, and will no doubt ultimately lead to the extinction of many species. With the exception of a few conspicuous insects, such as Argyrophenga antipodum, Chrysophanus salustius, the larger members of the genera Crambus and Leucania, the Lepidoptera frequenting the lowland tussock plains are not of very general interest. A number of typical species from these localities is shown in the accompanying drawer. It should be mentioned that the silver stripes on the underside of the hind wings of A. antipodum, and the long white stripe or stripes which form such a typical marking on the upper surface of the fore wings in the species belonging to the genus Crambus, are both protective to an astonishing degree. Although these markings do not appear to resemble blades of grass when the insect is examined by itself, yet when specimens are in situ amongst the actual grass the protective value of the striped colouring is very evident, and renders the discovery of the specimens a most difficult matter. It is therefore probable that the striped colouring produces the same general effect on the eye as the varieties of light and shade which exist in a tuft of grass growing under natural conditions.
So efficient is the protection afforded by the colouring of grass-feeding Lepidoptera that it is practically impossible to collect amongst tussock-grass except in fine calm weather, when the insects are either actually on the wing or easily disturbed from the tussocks. I have a very lively recollection of the difficulties experienced in finding even a few specimens of very common insects amongst tussock-grass in bad weather. On one occasion I was on a visit to the Mount Arthur tableland, and we had experienced extremely wet and stormy weather for some days, which prevented collecting of any kind. Following this we had a day of very cold wind with an overcast sky, and, being at last able to venture outside the door of the tent we determined to search for insects amongst the tussocks, as there was absolutely nothing on the
wing. Spending some two or three hours in this way, we succeeded in finding only three or four specimens of the extremely abundant Crambus crenæus; but had the weather been warm and the insect flying we certainly could have taken fully ten times as many specimens during the same interval of time.
The larvæ of such of the grass-feeding Lepidoptera of which the transformations are known are also protected by a striped pattern of colouring; but the life-histories of many of these still remain to be discovered, probably owing to their very efficient means of concealment.
This is probably the most interesting class of collecting we have in New Zealand, but it is not, to my mind, nearly so important a branch of work for this generation of naturalists as the collection of specimens in the lowland forests. Mountains of less than 3,000 ft. in height are in places extensively used for agricultural purposes, and the flora of these localities will consequently be subject to modification and extinction, insect fauna sharing a similar fate; but the flora of the higher mountains is not likely to be much influenced by cultivation, and hence I consider that the immediate formation of collections of the higher alpine species, although of great interest, is not so important to the interests of future science as the preservation of examples of species inhabiting the rapidly disappearing forests. Nevertheless, collections of the mountain species in New Zealand are great desiderata, and as these generally comprise some very attractive insects some of our entomologists may be interested in a short account of such limited experiences of mountain collecting as I have enjoyed.
So far as Wellington is concerned, probably the most accessible locality for a great variety of mountain species is the Mount Arthur tableland, in the Nelson District. As I have already given an account of the entomological resources of this locality in the “Transactions of the New Zealand Institute” for 1889, I will not occupy your time this evening with any more detailed account; but I must remark that subsequent visits have impressed me still further with the absolute necessity for the erection of some sort of permanent shelter in the locality that might be available for the use of naturalists. By a combined movement on the part of a few entomologists and botanists this might be easily arranged.
I should perhaps explain that the meteorological conditions which frequently obtain on the tableland of Mount Arthur, even in the middle of summer, are such as to render
a tent a most uncomfortable, not to say highly inefficient, habitation, this condition being further enhanced by the rising of the mountain torrents, which renders retreat to the nearest house—twenty miles away—impossible. I believe, however, that foot-bridges have been placed over all the larger torrents since my last visit (1898); but, notwithstanding this, I can assure you from extensive experience that, except to a person of unusually robust health and heroic temperament, the tableland of Mount Arthur is not a place at which to stay without a house of some description.
Daring January, 1893, I visited Castle Hill, a well-known locality on the main road between Christchurch and Hokitika. This spot may be said to mark the beginning of the forests, which become denser and more luxuriant as the West Coast is approached. The weather here was very good, and the heat extreme; in fact, it is without doubt the hottest place I have ever visited in New Zealand. Our camp was situated at an elevation of 2,500 ft., and several interesting species occurred in the surrounding birch forest. The mountains here are fairly high, Mount Enys, the highest point attained, having an elevation of over 7,000ft. On the summit of this mountain I observed a large number of a species of ladybird (Coccinella novæ-zealandiæ). They were extremely abundant, and swarming in all directions over the rocks. It is known that these insects frequently migrate for long distances in great swarms, and on one occasion it is stated that the dome of St. Paul's Cathedral in London was red with ladybirds. From these facts I am inclined to think that the large assemblage of ladybirds I observed on the summit of Mount Enys was a migratory swarm, as there was no vegetation there to support the large number of aphides, or plant-lice, which would have been requisite to have supplied so many ladybirds with food during their larval condition.
The spur leading up to Mount Enys is a very long one, but extremely broad and easily traversed. It is really an extensive mountain-chain; and one could walk many miles along the Craigieburn Range at elevations of from 6,000 ft. to 7,000 ft. There were only a few patches of snow on this range at the time of our visit, and on one of these I saw a number of birds with rather long legs and bill, short tail, greyish wings and back, and cream-coloured breast. These birds were busily engaged pecking at some objects in the snow, but I was unable to ascertain the nature of their quest.
During this trip I secured a few specimens of Erebia pluto, at elevations of about 4,800 ft. They were larger than those taken on the mountains in the Nelson Province, but smaller than some I subsequently captured on the ranges at the head of Lake Wakatipu. Although four or five new
species of moths were discovered as the result of this expedition, I cannot say that I regard Castle Hill as a first-class locality for entomological work.
Probably the ideal spot for alpine collecting in New Zealand is Mount Cook Hermitage. Here the collector has all the comforts and conveniences of a first-class house, and is actually in the midst of a subalpine fauna and flora. During last December I visited this locality, and was fortunate enough to take, amongst other things, a new species of Declana (D. glacialis), which I exhibit this evening. I propose to describe this insect, with several other new species of Macro-lepidoptera, at a subsequent meeting during the session.
My visit to Mount Cook was unfortunately limited to five days only, of which three were more or less wet, so that my entomological investigation of the district is at present extremely imperfect, especially as my energies were very much impaired at the time by an attack of influenza. In spite of these very great drawbacks, however, I saw and obtained a considerable number of novelties, and feel confident that a more prolonged visit a little later in the season—say, from the middle or end of December until the end of January—would be productive of extremely satisfactory results. The great advantage of Mount Cook as an entomological locality is the high altitude (2,500 ft.) of the collector's headquarters. In two or three hours an elevation of over 4,000ft. can easily be attained, the greatest number of species being found between these limits of elevation. As a matter of fact, very few insects are found above 6,000 ft., and, so far as collecting is concerned, it is quite unnecessary to ascend above this altitude.
During my visit to Mount Cook my explorations were practically confined to the immediate neighbourhood of the Hermitage—i.e., the terminal moraine of the Mueller Glacier, the Hooker River, and the Sealey Range. The first-named locality was the most productive, and was at that season (early December) covered with most beautiful specimens of alpine flowers, the handsome Ranuniculus lyalli being the most conspicuous. Some very fine grasshoppers were found here, notably Brachaspis nivalis and Paprides nitidus, and allied species. The first named is a large greyish-brown species, and was found abundantly on the bare moraine close to the ice. The species, unfortunately, have faded very much since they were killed, and their appearance is thus so much altered that I am satisfied, for accurate work, it is essential that descriptions and illustrations of these insects should be made from living specimens. This remark applies, in fact, to all species of bright-green grasshoppers, many of which are extremely beautiful. Diptera were very abundant on the
lower portions of the moraine, where vegetation was luxuriant, and I secured several species not previously taken.
On the Sealey Range I found insects very abundant up to about 3,800 ft., taking on the way up several fine examples of the very rare Notoreas strategica. Above 3,800 ft. there were many patches of newly fallen snow, and the surface of the ground was very wet and cold. Here were absolutely no insects, so that I did not proceed further up the mountain.
During this visit I did not see any specimens of the mountain butterflies Erebia pluto and Erebia butleri, but I think I was fully a week too soon for them. No doubt a few really hot days would have made a great difference, and it is almost certain that Erebia pluto must be an abundant species in the Mount Cook district, and probably also E. butleri occurs there.
During my return journey I had an hour's collecting on the banks of Lake Tekapo. Although nothing of a very striking nature was to be found, I obtained several peculiar little local species, amongst which I may mention Lythria euclidiata. From this I am inclined to think that it would reward an entomologist who had plenty of time to spend a day at Lake Tekapo. It would be necessary, however, to select a perfectly calm, sunny day, as there is no shelter in the locality, the country being quite open and covered with tussock-grass; and all those species I observed were resting in hot sunshine on the stones-near the edge of the water.
Another extremely interesting entomological locality is the western side of the head of Lake Wakatipu. Here I had the good fortune to spend a week in 1894, with the most satisfactory results. In fact, I think the Humboldt Range is the richest mountain locality I have ever visited, and its interest is further enhanced by the presence there of the extremely local Erebia butleri. Until January, 1894, when I found the insect abundant on the Humboldt, only three damaged specimens had ever been taken. These were discovered by Mr. John D. Enys on Whitcombe's Pass, Canterbury, in March, 1879. On the Humboldt Range the forest terminates at about 3,600 ft. above the sea-level—that is, an altitude of 2,600ft. above the level of the lake. The ascent of the lower portion of the range is very tedious, owing to the quantity of burnt bush that has to be traversed, and a good track might be made with great advantage. Once clear of the bush the travelling is fairly good, but there are many cliffs which require to be carefully watched when the collector is busily engaged in the pursuit of insects. These cliffs are often overhanging, and dripping with water. Their surfaces are nearly always fringed with a luxuriant growth of alpine plants, and it is amongst this vegetation that many rare species of alpine moths abound.
I have much pleasure in exhibiting a drawer of characteristic insects from the Humboldt Range. Amongst the more interesting species in this box may be mentioned Erebia butleri, Xanthorhoe catiaphracta, Cerozodia plumosa, (I always regret that I did not secure a good series of well-set examples of this Tipula), a large weevil at present unnamed, and the very striking ichneumon-fly Rhyssa antipodum, which, by the way, also occurs at Mount Arthur. A host of smaller species could also be added.
There is no doubt that this range and the others in the neighbourhood, which are forest-clad at their base, would amply repay a further and much more exhaustive examination than has yet been given to them. Although I ascended the Humboldt Range on three occasions during my week's visit, I was only able to devote a few hours each time to actual collecting, so much time generally being lost in making the ascent and descent. To adequately work the range a permanent camp should be formed at about 3,000 ft. or higher, if possible, and expeditions made from this base in various directions.
As we fortunately have now several trained entomologists in the far south of New Zealand, expeditions on their part into the mountains at the head of either Lake Wakatipu or Lake Te Anau should not present any formidable difficulties or serious cost, and I feel confident that a thorough investigation of the insect fauna of these mountains would be rewarded by many interesting discoveries.
I should add that I spent three days on the eastern side of Lake Wakatipu at Glenorchy, but found the ranges there comparatively barren of insect life. These ranges are bare from base to summit, having no trace of forest on them, and they well exemplify a fact which I mentioned before—i.e. that the most productive mountains for entomological work are those rising out of dense forests. I have invariably noticed this in all my entomological expeditions in New Zealand.
Before concluding this address a few remarks on the value of field natural history and collecting as educational pursuits may not perhaps be deemed inappropriate. Although it is very probable that I am inclined to overrate the importance of natural-history studies generally, yet there are still some, even amongst scientific men, who I fear are inclined to undervalue the work accomplished by collectors. It should, however, be borne in mind that many of our most successful philosophers and scientists have sprung from the ranks of mere collectors, and have not all been produced by the more orthodox, though less original, methods of universities
and kindred institutions. Darwin may be fairly taken as a type of man whose unparalleled abilities as a naturalist and philosopher were largely due to his early experiences, firstly as a collector, and subsequently as an observer in the field. His marvellous powers were certainly not acquired by book-learning only, or by the passing of examinations, but almost entirely by original research and patient study in the field. There is no denying the fact that Darwin discovered the most far-reaching law that has yet been discovered in connection with biological science—i.e., the principle of natural selection or the survival of the fittest, a discovery which is only equalled by that of Sir Isaac Newton in astronomy. The fact that Darwin began his scientific career as a collector of beetles will, I trust, be taken by the Society as some excuse for the amount of time I have occupied in delivering an address on entomological collecting in New Zealand.