Lepidoptera Facts Searching For Moths At Night
It is a well-known fact that the night-flying moths are attracted by lights, a characteristic of these insects that it is difficult to explain. Their love of darkness is in many instances so decided that they absolutely refuse to take flight while the fading light of day still lingers on the horizon, and even display a great aversion to the rays of the moon; and yet these very same species will often rush madly into the fierce glare of a naked artificial light, or fly with an energy almost amounting to fury against the glass of a street lamp or lighted window.
Puzzling as this peculiar tendency is, we can profitably turn it to our own account by making it a means of luring a number of moths into our presence.
The simplest way of putting this mode of capture into effect is to post yourself at your open window, with net and cyanide bottle at hand, while the brightest light you can command casts its rays as far and as wide as possible into darkness outside. If you use an oil lamp for the purpose, let it stand just inside the window frame, or, if a jointed gas bracket happens to be situated beside the window, bend it round so that the rays may pass over a wide area outside.
Two such lights are sometimes a very decided advantage-one quite outside the window to attract the moths from all possible points, and then another near the middle of the room to invite them inside. Whether you use either one or two lights, always see that it or they are so surrounded by a screen that the moths cannot by any possibility rush into the flame. There is nothing better for this purpose than a covering of light gauze, for this is not only a barrier for the prevention of the suicidal tendencies of the insects, but it also gives a good foothold to those who would like to rest and enjoy the luminous feast.
You will soon begin to learn that moths, like ourselves, exhibit great differences in their ways of enjoying their festal moments. Some will satisfy themselves by flying near the light in almost a straight course, hardly slackening their speed as they pass; or will, perhaps, make a hurried curve round the light and then pass on at once about other business. To catch these you must be always on the alert, with net in hand, ready to make a dash at the right moment. But many will make straight for the flame, and then, finding a barrier in the form of gauze or glass, will either flutter round and round as if dissatisfied with your attempt to save them from an untimely end, or else settle quietly on the screen to enjoy the brightness for a long period. The flutterers are usually easily covered by a glass or the open cyanide bottle, and as for those that settle down quietly, you can take them at your leisure.
It will not do for a collector to depend solely on this method of obtaining moths, but at times when either his duties or the bad weather keeps him at home it affords him a means of capturing a few specimens that otherwise would have been missed. He may be even so busily engaged in other matters that he cannot afford the time to stand and watch with net in hand, but the insects that fly into his room and dance round the gas jet or inquisitively examine the white surface of the ceiling are easily netted or boxed without much loss of time.
The chances of success at this kind of work will vary considerably with the aspect, the season, and the weather. If your window opens on a large flower or fruit garden, on a patch of wooded country with plenty of underwood, a piece of waste ground overgrown with rank vegetation, or a stretch of heath or moor, then you may expect a very large number of visitors; but if you are situated on a level and barren country, or in the dense atmosphere of a thickly populated district, you must not reckon on many intruders.
As regards the season, this is more extended than that of the butterflies. A few species of moths may give you a call during the bleak nights of October and November, and also during the somewhat less dismal nights of February and March; but from April to September you may rely on a goodly number of captures. Of course you will not expect many of the ‘rarities’ and ‘gems’ to find you out; these are to be searched for in the open field in the manner to be presently described; but your lights will attract a large number of the commoner species of Geometra and Noctua, the former chiefly during the early summer, and the latter more or less throughout the season.
A little experience will show you that the atmospheric conditions form a very important consideration. The dark and warm nights are the most productive. Very little luck is to be anticipated when the full moon is throwing down her silvery rays from a clear sky; nor will you see many while a cold east or north-east wind is blowing. Under these conditions many moths prefer to keep in the sheltered nooks where they slept away the sunny hours of the day. They love a warm and moist air such as calls forth the odours of the fragrant blossoms that provide their sweets, and show no dislike to a fine drizzling rain that you yourself would prefer to avoid. A pelting shower will generally keep them under cover, but they delight in the fresh and moist air that immediately succeeds the passing storm.
If you reside on the outskirts of a town an occasional tour of inspection of street lamps may add a few specimens to your collection, and some entomologists attach so much importance to the value of these luminaries that they provide themselves with a special net for the removal of moths from the glass and rails (fig. 50). The straight side marked a is applied to the panes of glass when flutterers or settlers are to be taken, and the bend on the opposite side is to secure those that rest on the rail. Such a frame is easily made by bending a piece of stout wire to the required shape, and then soldering it to a ferrule to receive a long stick. The net itself should not be deep.
Many different forms of traps are now made for catching moths, and these are deservedly coming rapidly into favour. They are generally constructed on a ‘catch-’em-alive-oh’ principle, and have the advantage that, after having been set, they may be left alone all night without any watching, and give an ambitious collector the opportunity of taking insects in his garden and searching in the open field both at the same time.
One of these traps may be constructed as follows at the cost of only a few pence over the price of a small paraffin lamp. Put together a square box, the sides about two feet and the front open, or procure a suitable one from your grocer. Place a paraffin lamp with a bright tin reflector at the back of this, and make a hole in the top just over the chimney to allow the heated air to pass out freely. Three sheets of glass are now to be placed as shown in the sketch (fig. 51), one upright piece completely shutting off the lamp, and two others placed obliquely with a space between them just large enough to allow admission. These must be exactly the width of the box, and should not be permanently fixed, but simply resting on small wooden supports nailed on to the sides. When required for use, it is only necessary to light up the lamp, strew some dead leaves on the bottom of the box, and put the sheets in their places. It will be seen at once that the angles at which they are placed will direct all light-seekers into the lower compartment, whence they are not at all likely to find their way out again; and after vain endeavours to reach the light they finally settle down on the sides of the box or seek shelter among the dead leaves.
Occasionally it happens that an entomologist is lucky enough to claim the friendship of a person who, from the nature of his calling, is peculiarly well qualified to render him great assistance. Thus a friendly lamplighter, expert and patient in the use of the cyanide bottle or pill box, is capable of giving valuable aid at times; and the keeper of a lighthouse has it in his power to capture many a gem that is seldom seen on the wing; but, although much may be done by means of these and other stationary lights, this kind of work does not compare favourably with the night rambles of a naturalist in the very haunts of the objects of his search.
For such out-door work in search of moths a good lantern is essential. An ordinary ‘bull’s-eye’ is almost useless, for, although it concentrates a good light on certain objects, the narrow range of its rays constitutes a strong objection to its use for entomological work. For this purpose it is necessary that the rays of light not only pass in front of you, but also shoot off right and left to warn you of the approach of a moth before it is too late to wield the net. This wide range may be obtained by means of three flat glass sides, or, better still, by a bent plate glass front.
In addition to this you must go out provided with your net, killing bottle, and a number of pill boxes. Choose your night according to the hints already given, and if you are on the look-out for any particular species, be careful that the date of your outing is well timed, making any necessary allowances for the forwardness or backwardness of the season, for a moth that is generally due on a certain average time of the year may appear some weeks sooner if the preceding weeks have been unusually warm, or its emergence may be delayed considerably by the prevalence of cold east winds or a late frost.
Make up your mind as to the field of your operations before you start, and if possible choose a route that will carry you through a variety of situations, so that you may pass the favourite haunts of a number of different species. Clearings in woods with an abundant undergrowth, waste places with plenty of tall and rank vegetation, overgrown railway banks, clover fields, the flowery borders of corn fields, plantations in parks, heaths and moors, sheltered and overgrown hollows such as chalk pits and old disused quarries, reed and marsh land, all these are good localities, each one inhabited by its own peculiar species, and if your route runs through a fair variety of such places you may, other things being equally favourable, depend on a good catch.
See that your time also is well chosen. Of course you cannot say exactly what the night will be till it actually comes, and, as you have to start off before it is dark, you must consider the probabilities of the future from the present condition of the air. Let it be a night when a bright moon is not due, and if it follow a warm and moist day with a south or south-west wind, or if drizzly, so much the better; but let your feet be shod with boots that will permit you to wade through moist herbage without danger, and take a waterproof if necessary.
It is always advisable to be on your hunting ground before twilight sets in, as a number of moths venture out before the sun has disappeared; and then you can work on till midnight if you feel inclined, or even extend your labours till the early hours of the morning.
Before dusk you will meet with many of the little Tortrices in sheltered spots, and a little later the Geometra and Hawks will be on the wing. Thus, before dark, you may make good use of your net, dealing with your captures just in the same way as recommended in the case of butterflies.
After a time, however, the lantern will have to be brought to your assistance in making known the whereabouts of the later species, consisting chiefly of the Noctua, many of which do not make their appearance till it is quite dark. If now you carry your lantern in your left hand, your work will be rendered somewhat difficult and tedious, for, although one hand is sufficient to manage the net properly, you are compelled to rest your light on the ground every time you make a capture, as it is impossible to box your specimens unless both hands are quite free. This difficulty is easily overcome by suspending the lantern by means of a string or strap placed round your neck, allowing it to hang on your chest; and a further advantage is gained by having a second strap round your chest to prevent it from swaying about with every movement of your body. This arrangement gives you both hands perfectly free during the whole time, and also prevents the necessity of continually bringing yourself into a stooping or kneeling posture while you are examining or boxing the specimens you have netted.
There are now two courses open to you. Either you can kill and pin the moths as you catch them, fixing each one securely in the collecting box, or you may simply shut each one in a separate pill box and leave the remainder of the work to be done at home. If the ordinary collecting box only is used, a little of your time is necessarily occupied in pinning and transferring, and if many insects are about such an occupation may appear to you to be a waste of valuable time. But this is not all. Often and often will you find that while thus engaged a splendid moth will come and flutter round your light; and, before you have time to drop your collecting box and pick up the net, the fine creature you would have prized has darted off again. This certainly seems to speak in favour of the pill-boxing method, but it must be remembered that a few of the moths will continue to flutter after they have been boxed, so that when you arrive home they are more or less damaged, a large number of the scales that once adorned the wings now lying on the sides and bottom of the boxes. Perhaps the best plan is to take both the collecting box and also a quantity of pill boxes, and a little experience will soon show you which is the better accommodation for certain kinds.
Particular attention must be paid to flowers, some of which are very attractive to the Noctua especially. Sallow blossom in spring and ivy bloom in autumn should be carefully and frequently watched, and at other times the blossoms of heather, ragwort, bramble, clover, and various other flowers must be searched.
As you cast the rays of the lantern on the feasting moths some will prove themselves very wary, and dart away at your approach; but others will take but little notice of your advance, and will continue to suck the sweet nectar, their eyes glaring like living sparks.
As a rule the Noctua thus engaged are easily pill-boxed or caught direct in the cyanide bottle; but a few of the more restless species are to be made sure of only by a sweep of the net. Some will feign death as soon as disturbed, and allow themselves to drop among the foliage, where further search is generally fruitless.
Another common difficulty arises from the inconvenient height of many of the attractive blossoms-often so great that it is impossible to reach them with the net, and very difficult to direct the rays of your lantern on them. This is particularly the case with sallow and ivy, the flowers of which are two rich sources of supply to the entomologist.
Those who intend giving special attention to these blossoms should be provided with some form of apparatus that will enable them to extend their operations as high as possible. Perhaps the most effective arrangement is the well-known combination here figured. It consists of a long and stout stick, at the top of which is a tubular joint (fig. 52) that might be termed a T-piece were it not that the smaller part does not stand out at right angles to the other. In this is fixed, in a straight line with the stick, a short rod on which hangs a lantern-an ordinary bull’s-eye answers well here; and in the smaller tube is another short rod carrying a shallow basin-shaped net, and of such a length that the net is just in advance of the lantern.
At first sight this arrangement will strike you as being very unsatisfactory, there being no kind of trap to prevent the escape of the insects. But it must be remembered that moths are more or less addicted to habits of intemperance-that they will hold on to the supply of the sweet fluid they enjoy till they are ready to drop with intoxication. This being the case, some will fall into your net as soon as they are startled by the sudden and near approach of the glare of your lamp, and others are easily made to fall therein by gently tapping the flower-bearing stems from below with the edge of the ring.
Having become acquainted with this very sad propensity, which thus brings ruin to so many unfortunate moths, can we not yet further turn their evil doings to our own profit in our endeavours to become acquainted with their structure and history? Most certainly we can. All we have to do is to distribute in their haunts a bountiful supply of some artificial intoxicant such as they love, and then lie in wait for the victims that fall a prey to our snare. This process is known to entomologists as ‘sugaring,’ and is a splendid means of securing an abundance of species, often including some rare ones that are scarcely to be obtained by any other plan. Let us now inquire into the modus operandi of this interesting operation.
The first thing to do is to prepare the luring sweetmeat. Supply yourself with a quantity of strong, dark treacle, and also some dark brown sugar; always remembering, in the selection of these viands, that odour rather than purity is to be the guide. The best kinds of sugar are those very dark and moist brands imported in a raw state from the West Indies, nothing being better than that known as ‘Jamaica Foots.’
Mix about equal quantities of these with a little stale beer, and boil and stir till all the sugar is dissolved. The consistency of the mixture should be such that it will work well with a brush when used as a paint-not too thick, nor so thin that it is easily absorbed by the substance on which it is ‘painted,’ nor must it be in such a fluid condition that it easily runs.
When satisfied on these points, transfer the mixture to a tin canister, see it properly covered, and set it aside as your ‘stock’ from which you can draw supplies as required. Now secure an ordinary painter’s brush of convenient size, and a number of strips of linen or other rag, each one of which is fastened to a hook formed of bent wire. These items, together with the usual lantern, collecting box, pill boxes, and killing bottle, complete your outfit for the sugaring expedition.
When the selected time for operations has arrived, take sufficient ‘sugar’ for your night’s work, mix it well with sufficient strong rum to give it a very decided odour, and start off at dusk with this and the other requisites just mentioned.
The night chosen should be warm and calm, with a rather damp atmosphere, and no moon preferred. Let your locality be a well-wooded one; abounding, if possible, with giant oaks and other trees, and containing open spaces with plenty of underwood and rank herbage. Such localities are to be met with at their best in forest lands, and if you would do wonders at sugaring you cannot do better than arrange for spending your holidays in such a spot as the New Forest, taking with you sufficient ‘sugar’ for several nights’ work.
Having reached a likely spot of no very great extent, you prepare for real work. Light up the lamp, and get out your sugaring tin and brush ready for action. Take your course along some definite track that you are sure to remember, painting vertical strips of sugar, about a foot long, on the trunks of trees or on palings, and hanging strips of rag that have just been steeped in the sugar on the branches of small trees and shrubs where you do not find good surfaces for the brush.
After satisfying yourself concerning the amount of sugar distributed, retrace your steps, examining every patch of sugar as you go. It will not be long before signs of life appear. Earwigs, spiders, centipedes and slugs will soon search out the luscious feast, but unless the time and the locality are ill chosen, the lantern will soon reveal a goodly number of moths, with eyes glaring like little balls of fire, greedily devouring the bounteous repast. These will consist chiefly of Noctua, but Sphinges, Geometra and numerous small species also join the company.
Some will exhibit a restless disposition, either darting off before you make a close approach, or keeping their wings in rapid vibration as if to be fully prepared for a hasty retreat when occasion demands. These must receive your attention first; and, having secured them, proceed to box as many as you require of the more lazy and gluttonous species.
As a rule, moths thus engaged are easily pill-boxed, but the livelier ones will not submit to such treatment without attempting to escape. The best way to secure these is either to cover them with the opened cyanide bottle (or its substitute), and replace the cork as soon as a favourable opportunity occurs; or to perform the same feat with a glass-bottomed pill box.
The advantage of the latter over the ordinary boxes will be seen at once. After the insect is covered, its movements can be watched, and so a favourable opportunity can be seized for snapping on the lid.
As already stated, some moths feign death when in danger, allowing themselves to fall in places where they are often quite safe from capture. Others allow themselves to fall simply because they have so gorged themselves with the intoxicating sweet that they can no longer maintain their hold. Both these classes of sugar seekers may easily be secured by means of a net commonly known as the ‘sugaring net.’
This implement is so simple in its construction that anyone can easily make his own. The frame may consist of two straight wires or canes fixed in a metal Y, and the other ends joined by a piece of strong string or catgut as shown in fig. 54. The net itself need not be deep. As soon as you reach a tree where moths are feeding on the sugar, press the string of the net against the bark just below them. The string at once assumes the form of the trunk so well that you may be sure of every insect that falls while you are boxing.
For this work both hands must be free, and this is easily managed in spite of the number of appliances called into service. The lantern is slung round your neck and secured by a strap round the chest. The ‘sugaring net’ has a very short stick, and just while you are engaged in boxing specimens, it may be gently held against the trunk by a slight pressure of the body. But such precautions as these are necessary only when the night worker is out alone. There are many circumstances, however, that render the work of two or more in company much more enjoyable than that of a single-handed entomologist. The labours are considerably expedited where a division enables each one of the night ramblers to take a particular portion of the work; and if there is such a person as a nervous entomologist, that individual should on no account go a sugaring in lonely spots on dark nights. Every rustling leaf gives such a one a start; all footsteps are those of approaching disturbers of the peace; and when at last the invisible landowner or his keeper, attracted by the mysterious movements of the lamp, greets him with his gruff ‘What’s your business here?’ then for the moment he forgets his enchanting hobby and wishes he were safely at home.
It is certainly advisable to take a friend, whether an entomologist or not, on such expeditions; and if you intend working on private grounds, always make previous arrangements with the property owner, that you may fear no foes and dread no surprises; for a sugarer is far more sure of success in his work if he keeps a cool head and has nothing to think about for the time being but his moths and his boxes.
A few hours at this interesting employment pass away very rapidly, and when midnight arrives there is often no great desire to leave off, especially when it is known that some species of moths are not very busy till very late at night. Still it is not advisable to surfeit oneself with even the sweets of life. Perhaps it is better as a rule to work the early species only on one night, and reserve another for the later ones. The searchings are then always carried on with vigour throughout, and the labours that are thus never made laborious ever retain their attractiveness in the future.
It has often been observed that, when sugaring has been carried on for a few successive nights in the same locality, the success is greater each night than on the one preceding it. Hence it is a common practice to work a chosen ‘run’ for two, three, or more nights in succession; and some collectors even go so far as to lay on the bait for a night or two previous to starting work. For the same reason it is often advisable to continue the use of a fairly productive beat rather than to wander in search of a new one.
In the neighbourhood of large towns one may often meet with patches of sugared bark that mark the course and extent of a brother entomologist’s beat, and such are valuable to an inexperienced amateur in that they give him some idea of the nature of the localities that are chosen by more expert collectors. But it must be remembered that each entomologist has a moral right to a run he has baited, and that it is considered ungentlemanly, if not unjust, to take insects from sugar laid by another. I have sometimes seen cards, bearing the names of the collectors and the date of working, tacked on to baited trees and fences, thus establishing their temporary exclusive rights to the use of their runs. Such precautions are not necessary in large tracts of forest land, where the choice of runs is practically unlimited.
There are two other modes of capture available to the moth collector-the use of decoy females, and the employment of ‘sugar traps’-and both these may be used on the sugaring run, or at other times either in the woods or in your own garden.
The wonderful acuteness of the sense by which the males of certain species are enabled to seek out the females has already been alluded to, and the possession of a suitable decoy will often bring you a number of beautiful admirers without the least trouble, except that taken in securing the decoy and preparing her temporary abode. It is absolutely necessary that the female moth be one that has recently emerged, and consequently you had better secure her in one of her earlier stages, either by previous rearing or by collecting the pupa.
A little cage composed of a framework of wire covered with gauze must now be made. Perhaps the simplest pattern is that illustrated. Here the gauze is attached to two wire rings, only a few inches in diameter, and suspended by a string. Such a cage answers every purpose in the field, and has the advantage of folding into an exceedingly small space when not in use. It may be suspended in your garden or taken into the field whenever you have a suitable decoy at your disposal.
The sugar trap may be of much the same pattern as that in which a light is used, but if intended for field work it should be of a convenient size for portability. A lighter and far more convenient form may be constructed as follows:
Procure a large cylindrical tin box, and cut a circular piece of perforated zinc just small enough to drop into it. Then make two wire rings, one a little larger than the top of the tin, and the other only about an inch in diameter. Next make a conical net of leno, open at both ends, and of such a size that the two rings may form the frames of its two extremities. When the trap is required for use, cut a circular piece of flannel or other absorbent, steep it in sugar that has just been flavoured with rum, and place it in the bottom of the tin. Then place a few pebbles of equal size around the sides to support the zinc partition, drop in the partition, and then allow the net to hang on the rim as shown in the sketch.
This arrangement will explain itself. The moths, attracted by the sweet perfume, flutter about in the net till at last they find their way through the small ring. Once in, they make further attempts to reach the sugar; and, at last, finding all efforts fruitless, and, like Paddy at the fair, not being able to discover the ‘entrance out,’ they finally settle down in a disappointed mood awaiting your pleasure.
Perhaps another word of explanation is necessary here. Why not allow the poor creatures to reach the sugar that attracted them to the spot? The reason is this. They sometimes gorge themselves to such an extent that their bodies, dilated to the fullest capacity with syrup, are a bit troublesome when the insects are placed in the cabinet. It is therefore advisable to see that the zinc is so far above the sugar that the moths are unable to reach the latter by thrusting their extended proboscides through the perforations. A few dead leaves scattered on the zinc is also a useful addition, since it affords shelter to such of the insects as prefer it.
This is a very useful trap to keep in one’s garden throughout the season. It may not attract large numbers, but it has the advantage that it requires no watching. It is simply necessary to set it at dusk, and remove the captives in the morning or at your leisure.