An elementary manual of New Zealand entomology

by G. V. Hudson

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 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, 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.

CHAPTER III

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.