Part 5

{16}The cages I have been in the habit of using are made of two or three thicknesses of cardboard bent round into a cylinder and strongly pasted together. They may be of various sizes, from three to four inches in diameter up to eight or ten, and constructed so that one will go inside the other. The height should exceed the diameter by about one and a half inches. The cylinders should be made so as to stand exactly level on a flat surface, and they should have two rows of small openings round the sides for the admission of air. It is a good plan to have four of these openings in each row and place them opposite one another. They should be covered on the inside with gauze, stiffened with green or brown paint, as the dark colour will enable the observer to see inside more readily. A circular piece of glass is fitted into the upper end of the cylinder, and fixed by means of paste and paper. The base of the cage consists of two round pieces of wood, one about half an inch smaller than the other, the smaller one nailed exactly in the centre of the larger piece. These are made so that the cardboard cylinder fits accurately on the outside of the smaller piece of wood. The whole cage is then neatly covered with white paper inside and brown outside. A complete view of the interior can of course be obtained by looking in at the top, while the cages can be stowed away one within the other when not in use. A stone ink-bottle should be put on the floor of each cage and filled with water, into which a sprig of the food-plant can be introduced. Care must be taken to plug up the mouth of the bottle, so that the larvae may not crawl down the stem of the plant into the water and thus meet with an untimely end. This may readily be done by means of a cork with a hole bored in it for the stem to pass through, or a plug of moss or blotting-paper. Members of almost all the orders can be reared in these cages, as jam-pots full of earth may easily be introduced, in the place of the stone {17}bottle, when required for species which bury. A circular piece of blotting-paper should be placed over the bottom of each cage, while larvæ are feeding in them, and renewed when at all soiled. The excrement must also be removed when the larvæ are supplied with fresh food. As a rule, this is only necessary about twice a week, as the water will keep most plants fresh for quite a lengthened period. When it is necessary to remove a larva it should always be done with a fine camel-hair brush, never with the fingers. Generally, however, it is better to allow the larvæ themselves to crawl from the old sprig on to the new one, which they usually do in a few hours after the food is changed. The old plants should of course then be taken out so as to afford more room for fresh air.

Many female moths may be induced to lay their eggs in captivity, especially if put in a box with some of the food-plant of the larva. It is extremely instructive and interesting to rear an insect from the egg. When the young larvæ first emerge they must be kept in a tumbler with a piece of glass put over the top, as they might escape through the ventilators of the cages, but they ought to be transferred immediately they are large enough. When rearing a lot of caterpillars from a batch of eggs, care should be taken to avoid overcrowding.

A collection of insects should always eventually be placed in a neatly constructed cabinet. They should be arranged in rows, systematically, with the correct names under each species, and the name of the order or group at the commencement of each drawer. Numerous modifications in arrangement are often needed to meet the requirements of different sized insects, but an inspection of any good collection will at once explain the general principles. Camphor should be pinned in the corner of each drawer or store-box, and the whole collection fumigated with carbolic acid, or equal parts of oil of thyme, oil of anise, {18}and spirits of wine, every six months. These can be introduced in a watch glass containing a small quantity of the chemicals on a pellet of cotton-wool, care being taken not to stain the paper at the bottom of the drawer. For the same reason, while using carbolic acid, the camphor should be taken out, as otherwise it will "sweat." All boxes for the reception of insects must of course be lined with cork and paper.

It is most important that an accurate record should be kept of every specimen that is placed in the collection. This may be done by attaching to the pin underneath each insect a small numbered label, which refers to a book containing locality, date of capture and other particulars.

I have found it a good plan to give every species a number, and every specimen a letter. Thus, supposing Vanessa gonerilla is numbered "6," the first specimen taken would be "6a," the second "6b," and so on, all the specimens, perhaps, having different dates and localities. This system is very convenient when specimens are sent away to be identified by another entomologist, as, provided the collector always retains a single specimen of the species which he desires named, it obviates the necessity of having his specimens returned, the number showing at once to what species the name refers. At least five lines should be allotted to each species in the collection journal, and the writing should be small but distinct.

A collection formed in this manner will not only be a constant source of pleasure to the collector and those who succeed him, but very probably of great value in deciding many important questions in entomological science.

{19}CHAPTER III

The Coleoptera.

The observations on the natural history of the New Zealand beetles, forming the subject of the present chapter, are much less numerous than might have been expected from the great number of species which have been described. The difficulties attendant on rearing these insects are, however, very great, and it thus happens that the life-histories here given bear a smaller proportion to the number of the Coleoptera than will be found to be the case with the majority of the other Orders. I hope, however, that the few details I have collected, referring to the following species, may induce some of my readers to investigate others for themselves.

Group GEODEPHAGA.

Family Cicindelidæ.

Cicindela tuberculata (Plate I., fig. 1, 1a larva).

This is a very abundant insect found throughout the country in all dry situations. It delights in hot sunshine, and may be constantly observed flying from our footsteps with great rapidity as we walk along the roads on a hot summer's day.

Its larva (Fig. 1a) is an elongate fleshy grub, the head {20}and first segment being horny and much flattened, and the body provided with two large dorsal humps, each bearing at its apex a slender curved hook.

The burrows of these insects are very conspicuous, and must have been noticed by every one, in garden paths, sandbanks, and other dry situations; they are sometimes very numerous, and may be best described as perfectly round shafts, about one line in diameter, and extending to the depth of three or four inches, generally slightly curved at the bottom. The sides are perfectly smooth, and the larva may be often discovered near the mouth of its burrow, using its dorsal hooks to support it, and thus having both legs and jaws free to dispose of the unfortunate insects that fall into its snare. These usually consist of flies and small beetles, which appear to be urged by curiosity to crawl down these pitfalls, and thus bring about their own destruction. By reference to the figure it will be seen how admirably the hollowed head and prothorax serve the purpose of a shovel to the larva, when forming its shaft. These burrows are first observed about the middle of November; the perfect insects coming abroad three weeks or a month later, when they may be often seen in the neighbourhood of their old domiciles. They are very voracious, devouring large quantities of flies, caterpillars, and other insects, some of which are much superior to themselves in size. On one occasion I saw a male specimen of Cicindela parryi (a species closely allied to but smaller than C. tuberculata) attack a large Tortrix caterpillar, an inch and a half in length. The beetle invariably sprang upon the back of the caterpillar and bit it in the neck, being meanwhile flung over and over by the larva's vigorous efforts to free itself from so unpleasant an assailant. During the fight, which lasted fully twenty minutes, the beetle was compelled to retire periodically to gain fresh strength to renew its attacks, which were eventually {21}successful, the unfortunate tortrix becoming finally completely exhausted. The beetle devoured but a very small portion of the caterpillar, and abandoning the remainder went off in search of fresh prey. Eight other closely allied species of Cicindela are described by Captain Broun in the "Manual of the New Zealand Coleoptera," but they offer no especial peculiarities, and C. tuberculata may be taken as a type of the genus.

Family CARABIDÆ.

Pterostichus opulentus (Plate I., fig. 3, 3a larva).

This fine beetle is very common in most wooded situations in the Nelson district; it may be at once distinguished from the numerous other closely allied species by the beautiful metallic coppery tints that adorn its thorax and elytra.

During the day it is usually discovered concealed under logs and stones, and when disturbed, rushes into the first crevice to get out of the light. At night time, it comes abroad to feed, killing an immense number of flies, caterpillars, and other insects, to satisfy its voracious appetite. Although of a most ferocious disposition, it is not wanting in maternal affection. The female, when about to deposit her eggs, excavates a small cavity nearly three inches square, in which they are placed. These she broods over until hatched, and probably some little time afterwards, as I have found a specimen close to a nest, which contained both eggs and larvæ, and the zealous mother furiously bit at anything presented to her. The eggs are oval in shape, quite smooth, and yellowish white in colour. The young larva is drawn at Plate I., fig. 3a; it is remarkable for its superficial resemblance to a small Iulus, and being found in similar situations to that animal, its mimicry has probably some useful object. The older larva differs chiefly in having the head and thoracic segments proportionately {22}smaller. Twenty-one closely allied insects belonging to two genera are described by Captain Broun in his Manual, the largest being Pterostichus australasiæ, which is found in similar localities to the present species, but is not so common.

Group HYDRADEPHAGA.

Family DYTICIDÆ.

Colymbetes rufimanus (Plate I., fig. 4, 4a larva).

This insect is found plentifully in all still waters during the summer months. Its larva is a soft elongate grub, provided with six slender thoracic legs, and a pair of powerful mandibles. The posterior extremity of the body is furnished with two curious appendages bearing a spiracle at the apex of each, which the larva frequently protrudes above the surface of the water. The air is taken in through the spiracles, and conveyed to all parts of the body by two main air-tubes, one of which springs from each spiracle, and branches throughout the insect in every direction. During the spring months the larvæ may be found of various sizes in similar situations to the imago; they are very voracious, devouring freshwater shrimps, Ephemera larvæ, and occasionally, when pressed by hunger, they will even destroy individuals of their own species for food. These they capture by means of their powerful mandibles, retaining a firm hold of the victim until they have consumed all the fleshy portions, the rest of the carcase being thrown aside, and a fresh search made for more. One individual I kept for some time, remained perpetually concealed in a small patch of green weed, growing in the middle of its aquarium. In a short time it became surrounded with the skeletons of small water shrimps which had been seized by the larva as they passed by its hiding place, the unfortunate crustaceans only discovering their enemy when it was too late. I have not yet observed the pupa of this {23}insect, but it probably does not differ materially from those of its European allies. Although so very different in general appearance to the preceding insects, this beetle will be found on careful examination to agree with them in all important respects, being only what a ground beetle might naturally become if forced to lead an aquatic existence. Breathing is effected in all the water beetles by the spiracles of the abdomen, which alone are developed. The air is taken in between the elytra and the body, and owing to the convexity of the former, a supply can be retained sufficient to last the insect some twenty or thirty minutes. The beetles may be often observed with the extremity of their elytra protruded above the surface, renewing their supplies of air. On very hot days C. rufimanus may be occasionally seen flying with great rapidity far away from its native ponds. When doing so it makes a loud humming noise, and is a much more conspicuous object than when in the water.

Group CLAVICORNIA.

Family NITIDULIDÆ.

Epuræa zealandica.

This curious little beetle is found abundantly in the neighbourhood of decaying fungi, throughout the year, being most plentiful in the autumn and early winter. Its larva is a small cylindrical grub, with the head and legs so minute that they are scarcely perceptible, causing it to closely resemble the maggots of many dipterous insects, occurring in similar localities. It is generally found in the large yellow fungi, so abundant in wet situations during the late autumn and winter months. It forms numerous galleries through the plant in all directions, and owing to the large amount of moisture which is usually present, these galleries are often filled with water, so that the insect may {24}be said to be sub-aquatic in its habits. I have not yet detected the pupa of this species, although the discovery of a large quantity of both larvæ and perfect insects is of everyday occurrence with the entomologist in winter.

Family ENGIDÆ.