Could we with certainty discover the stations in which insects after their excursions take their repose, we might capture many that we now search for in vain. Several of these stations were pointed out in a former part of this letter where I detailed their usual haunts. I may here add, that numbers of them, when reposing, conceal themselves from their enemies on the under side of the leaves of trees and plants. Moths, especially the Noctuidæ, may often be met with in woods, as before observed[1553], on the north side of the trunks of trees. Mr. Marsham related to me, that once a little before sunset, observing over his head a number of insects on the wing moving on in one direction, he caught some of them, and they proved to be Labia minor. Struck with the circumstance, he watched them several evenings; and on one, as he was looking about a melon-pit for insects, he saw these little animals alight on the frame, hastily fold up their wings, and entering under the glasses, run down its sides and bury themselves in the loose earth. This he observed repeatedly. The onward flight of these insects was therefore evidently their return from their diurnal cruise to their nocturnal station.—This happened in September.
I am, &c.
[LETTER L].
ON ENTOMOLOGICAL INSTRUMENTS; AND THE BEST METHODS OF COLLECTING, BREEDING, AND PRESERVING INSECTS.
Having in my last letter given you some account of the haunts of insects, I now proceed to describe the various instruments with which you ought to be provided, to enable you to collect them; and the best mode of employing each. The Entomologist when he makes an excursion should have three principal objects in view, for which he ought to be duly prepared. The first is to find insects, the next is to catch them, and the last when taken to bring them safe home. In exploring their haunts he must also recollect that some will be reposing; others feeding; others walking or running; others flying; others swimming; others lurking in various places of concealment, and in different states of existence; and that he must be prepared with means of coming at and capturing them under all these circumstances.
1. First furnish yourself with a strong knife or other instrument with which you can raise the bark or penetrate the wood of any tree, when circumstances indicate that insects are busy below the one or within the other. There is no better tool for this and other purposes than Mr. Samouelle's digger, which consists of an iron five inches long, rather more than one-third of an inch in diameter, forming a curve towards the extremity, terminating in a lozenge-shaped point, and strongly fixed in a wooden handle[1554]. With this you may not only explore the interior of timber-trees, but grub up the turf under them, and examine the earth for the pupæ of Lepidoptera. When your object is merely this latter purpose, a potato-fork—which is better than a spade, as it will seldom injure the pupæ—will be your best implement.
2. Next have a stick, to resemble a common walking-stick, sufficiently stout to beat the branches of the trees and shrubs, fitted at one end with a male screw, and at the other with a female, with a brass cap to screw over each to keep the dirt from them. Besides this, you may carry with you a spare piece or two about a foot long, properly equipped to screw to it when you want to lengthen it.
3. Another implement must be a bag-net[1555]. This consists of a hoop of stout brass wire about nine inches or a foot in diameter, with a socket to receive the end of your stick, or, what is more secure, a screw to fix it to it, with a bag of gauze, muslin, or fine canvass, about twelve inches deep, sewed round it. The French collectors use a net of this kind, in which the hoop is formed of two semicircular pieces of iron or brass wire hooked together at one end, and at the other made to lap over the corresponding piece, and pierced to receive the screw at one end of your stick. When not employed, they double the hoop and conceal it under the vest; they fix to it a muslin bag of two feet long. This net is made to serve various purposes. With it they catch Lepidoptera and other flying insects; and an adroit collector by giving it a certain twist completely closes the mouth, so as to prevent the escape of his captives. Fixed to a very long pole (Mr. Haworth says it should be twenty or thirty feet long[1556]), it is the best net for the purple emperor butterfly (Apatura Iris). It is also used with success to push before you through the grass of meadows, woods, &c., and thus often displaces numerous insects, which fall into it;—every now and then it is examined, and the valuable captures secured. The common bag-net will perform the same operations, but is not deep enough for flying insects. If you lengthen your stick before you screw it on, it enables you to brush with it the weeds at the sides and bottom of ditches. This employment of brushing the grass, &c. may be carried on if you are walking with any friend not interested in Entomology, without much interruption of conversation. For this last operation—sweeping the grass, &c.—if you wish at any time to devote a morning wholly to it, you will find a net invented by the late Mr. Paul, of Starston in Norfolk, and which he employs to clear his turnips of Haltica Nemorum[1557], a very useful implement. The accompanying figure will give you a better idea of it than any description[1558]; you may make it large or small according to your convenience: the wider it is, the greater space it will brush at once. When your object is a more general investigation, the bag-net just described is preferable.