Movement of the International Literary Exchanges, between France and North America from January 1845 to May, 1846 / With Instructions for Collecting, Preparing, and Forwarding Objects of Natural History Written by The Professors Administrators of The Museum Of Natural History At Paris. And Instructions Relative to Anthropology and Zoology

by Unknown

Besides the insects that live as parasites on other animals should not be neglected.

Insects are easily caught and need few instruments. The best way to take a great number of these animals at a time is to throw quickly on the plants of the meadows and lawns a cloth sack whose mouth is attached to a circle of iron, fixed at the end of a stick. By directing this instrument alternatively right and left, even the fleetest insect cannot get out, and all those that are caught by its movement, are driven to the bottom of the sack; they should be taken out one by one, either with the hand or pincers, and pierced immediately with a pin proportioned to the size of the animal. The coleopters should be pierced on the right wing (clytze), the hymenopters, dipters and lepidopters in the middle of the waist, the orthopters and nevropters a little behind, between the base of the wings.

For the small kinds, it is better not to fix them in this manner, and to preserve those whose shell is hard enough, the coleopters and the most part of hemipters, for example, it is sufficient to place them in little bottles or in flacks full of rolls of paper (or even cotton, if paper is wanting). This way is even applicable to the great kinds and should be employed when there is not time to impale with care the insects that are caught. The small kinds with soft shells should be preserved in alcohol for drying frequently deforms them to such a degree that they cannot be recognised. It is, also, in this liquor that the caterpillars should be preserved, as well as other larvæ, and it would be well to place with them a certain number of dried insects so that a part might be taken for anatomical researches.

Butterflies are taken by the aid of a gauze net or pocket. The insects are found chiefly in fields whose flowrs abound and on the leaves of trees; but they must be sought too in dark places, for, during the day, the night kinds are here asleep upon walls or the bark of trees. With a little skill, they can be pierced without seizing them before hand, and if there is fear of missing them thus, they should be covered whith the gauze pinews, through which the pin can be passed. When the air is calm and the night obscure, they can be easily taken by means of torches, for it is sufficient to place a light in a low and open place to attract a multitude of phalenes and other nocturnal insects. But to have handsome lepidopters, it is best to obtain caterpillars, feed them with the leaves of the plant on which they are found, and pierce the butterfly as soon as he has undergone his change, for the specimens caught in their flight are rarely fresh.

For the coleopters, it is not sufficient to beat the bushes and herbaceous plants, these insects should, also, be sought under the bark of trees, in the interior of mushrooms, under the stones and even in the soil: for this, it is well to be provided with a paring-knife, an instrument which is much like a carpenter's chisel, but which is slightly curved, and ends in a kind of pointed spatula.

Aquatic insects are taken by the help of a net like that used for insects of the air, but whose bag should be of canvass instead of cloth. In fine, to catch the hymenopters, whose sting is often formidable, it is necessary to have a pincers whose prongs are disposed like rackets and armed with coarse lace.

The preservation of insects that have been pierced requires some care; to prevent the lepidopters from injuring their wings in struggling, it is well, directly they are caught, to press the throat down; but, generally, it is necessary, on returning from the chase to kill quickly all the insects that have been caught, and, to attain this end, the best way is to place them dry in a tumbler surrounded with boiling water, for a high temperature kills them in a few minutes. The boxes designed for the reception of entomologic specimens should be of light wood, and, at least, two inches and a half deep; the bottom should be lined with cork or some other very soft vegetable substance and the pins should be pressed in as much as possible. When the insects are large, it is necessary, besides, to fix them by means of several pins placed around; for if one of them gets loose, he not only injures humself, but likewise damages all those whom he jostles. As soon as a box is full, and the insects dry enough, it should be shut and pasted with bands of paper on all the joints; but in warm countries, where destructive insects abound, this precaution is not sufficient; the boxes should, besides, be placed in a tin chest soldered on all sides.

Arachnides.—Animal of this class are less numerous than insects, but they merit the attention of travellers; certain kinds live in the water, but the greatest part are land animals, and live in shrubs or in holes, either in old walls, or in the ground The industry that many spiders display in the construction of their dwelling or the snares designed to catch their prey, is very remarkable: the nests of the mygales, for example, is very curious. It would be interesting to have a collection of threads spun by exotic spiders, and the preservation of these delicate tissues is easy enough, if they are spread out on a leaf of paper dipped in gum-water. It is perhaps superfluous to add that those specimens would have little value, unless each one is accompanied by the spider that belongs to it. In fine, we will point out to travellers the kinds reputed venemous, and those which live as parasites on other animals.

The preservation of the arachnides offer some difficulties; in drying, those animals lose their shape, and in alcohol, their colors; so it is necessary, as much as possible, to preserve specimens of the same kind by both these processes, and to take care to number them so that they may be easily identified.

Crustacees.—These animals are almost all aquatic and the greatest part in the seas. Crabs are found generally near the shore in the hollows of the rocks and under the stones; but there are kinds which hide in the sand or which live at great depths; some live entirely in the sea. It is the same for the decapodes macroures, such as the langoustes and the salicoes; and it is generally by the aid of drags and nets that they are taken; but a more successful way of fishing is to sink to the bottom an open case, a kind of basket whose mouth is in the form of a reversed cone; some carrion placed in the interior of this snare attracts the crabs, and when once in they cannot get out.