Butterflies Worth Knowing Part 5

Nets in considerable variety and at various prices are offered in the catalogues of these firms. One can make, however, a net at home with little difficulty. One need only obtain an iron wire about one fifth of an inch in diameter and bend it into a circular ring a foot or fifteen inches wide, leaving the ends projecting at right angles to the circle and having a blacksmith weld them together so as to form a spur about four inches long. Now thrust this spur into some convenient handle, such as a broomstick, and sew over the wire circle a bag of mosquito netting, Swiss muslin, or some similar fabric. It is better that this material be green or black rather than white.

After the b.u.t.terflies are caught, they must be killed, so some form of killing bottle is necessary. Most collectors use a cyanide bottle, in which the fumes of cyanide of pota.s.sium kill the insects. One of the best ways to make this is to place in a wide-mouthed bottle two or three lumps of cyanide of pota.s.sium, approximately an inch across.

Over this place some fine sawdust and on top of the sawdust, pour liquid plaster of paris carefully so that it will harden into a layer about half an inch thick. Allow the plaster to become thoroughly dry, then insert the stopper into the bottle and it will be ready for use.

It is better to use a ground gla.s.s stopper so that the bottle will always be air tight. The sawdust is often omitted, the plaster of paris being poured directly over the cyanide. The special advantage of the sawdust is that it tends to absorb the cyanide in case it liquefies, as it often does in damp weather. As this cyanide is a deadly poison, it is better to let a druggist prepare the bottle or else to buy it already prepared of the dealers in such supplies.

[Ill.u.s.tration: b.u.t.terfly Envelopes. Fold first on line _AB_; then on _AD_ and _CB_; then on _BF_ and _EA_. (From Holland).]

After the specimens have been killed in the cyanide bottle, some method of keeping them is necessary. The simplest way is to preserve them with their wings closed together in pieces of paper folded over into triangles as indicated on the accompanying diagrams. Such specimens may be kept for an indefinite time and if one wishes to mount them later, it is only necessary to place them for a few hours in a relaxing jar, which is simply a closed vessel with enough water in the bottom to saturate the air with moisture. A great advantage of keeping the specimens in these paper covers is that they require so little room and are easily stored away in tin cans or boxes where they are safe from dust and destroying enemies.

[Ill.u.s.tration: Setting Board with b.u.t.terfly in place.

(From Holland)]

Those b.u.t.terflies which are to be preserved in the ordinary way, in drawers or cabinets, must be spread out and held in position while the body is drying so that the wings will remain expanded. For this purpose, some form of a setting board is necessary. These may be bought of dealers or made at home. One of the simplest kinds consists of two thin strips of pine board, a foot or more long, nailed to end pieces with a s.p.a.ce between the two boards wide enough to accommodate the bodies of the b.u.t.terflies. Beneath this open s.p.a.ce, a piece of thin cork is tacked. The pin on which the b.u.t.terfly is fastened is pushed through the cork until the wings of the insect are level with the boards. The wings are then brought forward with a needle point until they are in the desired position and they are then held in place by pieces of gla.s.s or by bits of cardboard fastened down by pins. The b.u.t.terflies must be left in this position until thoroughly dry.

[Ill.u.s.tration: Drying Box for Setting Boards. (After Riley)]

Special insect pins should be used for b.u.t.terflies. These are longer than common pins and have rounded heads. They are offered for sale by entomological dealers. Instead of pinning the insects and preserving them in cabinets, one may keep them in the Riker mounts, which have the advantage of being sealed so that there is no chance for dust or museum pests to reach the specimens. If one wishes to collect extensively, one will need a considerable number of setting boards and it will be worth while to prepare for them a special drying box like that shown in the picture above.

PART II

THE TRUE b.u.t.tERFLIES

SUPERFAMILY _Papilionoidea_

The great suborder of b.u.t.terflies is commonly separated into two princ.i.p.al groups called superfamilies. One of these includes all of the higher b.u.t.terflies and is named _Papilionoidea_. The other includes the lower Skipper b.u.t.terflies and is named the _Hesperioidea_. The former are characterized by small bodies and relatively large wings, straight clubbed antennae, and the fact that the caterpillars do not make coc.o.o.ns when preparing for the chrysalis state.

The most authoritative cla.s.sifications of b.u.t.terfly families are based upon the peculiarities of wing venation and are admirably discussed in such books as Holland's "b.u.t.terfly Book" and Comstock's "How to Know the b.u.t.terflies." Without attempting to go into the technical details of structure it will suffice here to give the list of families which compose the superfamily _Papilionoidea_:

The Parna.s.sians. _Parna.s.siidae._ The Swallowtails. _Papilionidae._ The Whites, Orange-tips, and Yellows. _Pieridae._ The Nymphs. _Nymphalidae._ The Satyrs or Meadow-browns. _Agapetidae._ The Heliconians. _Heliconidae._ The Milkweed b.u.t.terflies. _Lymnadidae._ The Long-beaks. _Libytheidae._ The Metal-marks. _Riodinidae._ The Gossamer-wings. _Lycaenidae._

It must not be thought that such a list necessarily indicates the degrees of development of the respective families, for this is not true. It is simply a linear arrangement adopted for convenience by leading authorities, notably Dr. Harrison G. Dyar in his standard "Catalog of American Lepidoptera."

THE PARNa.s.sIAN b.u.t.tERFLIES

FAMILY _Parna.s.siidae_

It is perhaps a bit unfortunate that the group of b.u.t.terflies, which is commonly chosen to head the list of families, is one that is rarely seen by most collectors. The Parna.s.sians are b.u.t.terflies of the far north or of high elevations in the mountains. The four species credited to North America have been collected in Alaska and the higher elevations of the Rocky Mountains, so there is very little probability of any of them being found in the Eastern states.

While, structurally, these b.u.t.terflies have a close affinity with the Swallowtails, one would never suspect it from their general appearance. Their bodies are large and all of the wings well rounded, so that there is more of the suggestion of a large moth than of the Swallowtail. The coloring is also more moth-like than with most b.u.t.terflies, the wings being very light colored and nearly transparent, with markings of gray and brown, arranged in dots and splashes.

All our species belong to the genus Parna.s.sius. The caterpillars show their affinity with those of the Swallowtails by having the curious scent organs or osmateria just back of the head. They feed upon such alpine plants as stonecrop and saxifrage and are well adapted by their structure and habits to the bleak surroundings of the mountain tops.

As a typical example of the environment in which these b.u.t.terflies live, we may take the alpine valleys of such mountain regions as Pike's Peak. Prof. M. J. Elrod has described a visit where, at an alt.i.tude of 11,500 feet in the month of August, _Parna.s.sius smintheus_ was flying by thousands, and the earlier stages were so abundant that a water ditch had the surface covered as far as one could see with the dead or dying caterpillars. In such situations, where ice forms at night, and snow frequently falls by day, these b.u.t.terflies develop apparently in greater numbers than almost any of our other species are known to do in warmer regions.

THE SWALLOWTAILS

FAMILY _Papilionidae_

This is probably the most distinctive family of all our familiar b.u.t.terflies. Its members are characterized by being on the whole the largest b.u.t.terflies in our region and by having the hind wings prolonged into curious tail-like projections, suggestive of those of a swallow. In general, the basal color of the wings is blackish though this is commonly marked in various striking ways with yellow, green, or blue, while the margins of the wings are commonly adorned with red or orange spots. These b.u.t.terflies are also characterized by certain peculiarities in the branching of the wing veins which will be found pictured in more technical works.

The caterpillars of these b.u.t.terflies have the characteristic form pictured on the plate of the Swallowtails opposite page _80_. When full grown they are large, fairly smooth-bodied worms, showing at most on the surface spa.r.s.e fine hairs or fleshy threadlike projections.

Their most characteristic feature is found in the scent organs called _osmateria_ situated in the back just behind the head. These are thrust out, generally, when the caterpillar is disturbed and appear as orange Y- or V-shaped organs from which an offensive odor is commonly given off. They are supposed to serve the purpose of preventing injury by enemies, possibly birds, monkeys, and other vertebrates.

Structurally, they are like long tubular pockets that can be turned inside out. When the pocket is in place it is getting a pocketful of odors. When it is inverted it lets these odors free. On this account Professor Comstock has aptly called these caterpillars "the polecats of the insect world."

When ready to pupate, these Papilio caterpillars spin a web of silk upon some more or less flattened surface and a loop of silk near by.

They entangle their hind legs in the former and keep their heads through the latter so the loop supports the body a little behind the head. Then they change to chrysalids which are held in place by these sets of silken threads.

The chrysalids are rather large and angular and generally take on colors approximating their surroundings. They vary so much in different species that one familiar with them can recognize the chrysalis and know the kind of b.u.t.terfly it will produce.

=The Black Swallowtail= _Papilio polyxenes_

While the Black Swallowtail is not so large as some other members of the group, it is probably the best known to most people. It is found throughout many months of the year in practically all parts of North America south of Canada, and has the habit of flying freely about fields and gardens in search of flowers from which to suck its nectar food, and of plants on which to deposit its eggs. The female b.u.t.terflies have a remarkable ability in selecting only members of the great family Umbelliferae for this purpose. In consequence the caterpillars are generally to be found feeding upon carrots, parsnips, parsley, and various wild species belonging to this order. (_See plates, pages 48 and 64-65._)

The eggs of the Black Swallowtail are laid one in a place upon the leaves of the food plant. Each egg is a small, yellowish, smooth, and ovoid object. It may often be found by watching the b.u.t.terflies as they fly low in search of umbelliferous plants, and seeing one stop for a minute or so while she lays the egg.

About ten days after the egg is laid it hatches into a small black caterpillar marked in a characteristic fas.h.i.+on with a blotch of white in the middle of the body which is suggestive of a saddle. The caterpillar immediately begins to feed upon the green substance of the leaf, continuing thus about a week before the first moult. At this time it does not change much in appearance, still being a spiny creature blackish in color and marked by the curious white saddle. A little later it moults again, retaining its original coloring. At each moult, of course, it gets larger and feeds more freely upon the celery or other plant on which it may happen to be.

When the caterpillar becomes about half grown it takes on a very different appearance from that of its early life. The skin is smooth rather than spiny, and the general colors are green, black, and yellow. The ground color of the skin is green, which is marked with black cross-bands along the middle of each body ring. On these bands there are many large dots of orange yellow, the whole coloring giving the insect a very striking appearance, especially when it is placed by itself against a plain background. When they finally become full grown in this larva state, these caterpillars are almost two inches long.

The larvae of the Black Swallowtail have certain characteristics in which they differ from many other caterpillars. After each moult they do not devour their cast skins, which happens in the case of many of their relatives. When feeding, as well as when resting, they remain exposed upon the leaf and seem never to attempt to conceal themselves, as is the habit with a large proportion of caterpillars. It is probable that this instinct for remaining exposed to view bears some relation to the curious means of protection possessed by this as well as other Swallowtail caterpillars. When disturbed one of these larvae will push out from just back of the head the strange-looking, orange-yellow Y-shaped organ which gives off a very disagreeable odor.

These osmateria organs are generally believed to be defensive against the attack of birds and various other enemies, although they seem not to be effective against insect parasites.

The full-grown caterpillars are likely to leave their food plants when ready to change to the chrysalis state. They wander in various directions until suitable shelter is found. A piece of board, a fence post, or possibly the bark of a tree will answer for this purpose.

Here the caterpillar spins a mat of silk in which to entangle its hind legs and a short distance away near the front end of the body it spins a loop of silk attaching the ends to the support. These serve to hold the chrysalis in place during this helpless period. After the loop is made the caterpillar keeps its head through it so that the loop holds the insect in position a short distance back of the head. It is now ready to moult its last caterpillar skin and become a chrysalis.

One who has watched hundreds of these caterpillars go through this change, Miss Mary C. d.i.c.kerson, describes the process in these words: "In this final moult the chrysalis has to work very hard. The bulk of the body is again slipped forward in the loosened caterpillar skin, so that this becomes tensely stretched over the anterior end, and very much wrinkled at the posterior end. The skin splits back of the head and is forced back by its own taut condition and by the efforts of the chrysalis, until only the extreme posterior end of the chrysalis is within it. Then the chrysalis withdraws this posterior end with its many very tiny hooks, from the skin on the dorsal side, and, reaching around, securely fastens the hooks into the b.u.t.ton of silk. Then the old skin is removed both from its fastening to the chrysalis and from its attachment in the b.u.t.ton of silk."

A short time after the caterpillar's skin has thus been cast off the chrysalis takes on a brownish color which as is so often the case is likely to vary somewhat according to the tint of the surrounding surfaces. This is doubtless a protective device and helps the insect to escape attack by birds during the long period of exposure. For this b.u.t.terfly pa.s.ses through the winter only in the chrysalis condition, and the larva which went into the chrysalis in September does not come out as a b.u.t.terfly until the following May or June. There are, however, two broods of the b.u.t.terflies in the North and at least three in the South. As the adults live for about two months and there is considerable variation in the periods of their development it happens that one can find these Black Swallowtail b.u.t.terflies upon the wing almost any time in warm weather, either North or South.

=The Giant Swallowtail= _Papilio thoas_

The largest of our North American b.u.t.terflies is a magnificent insect with a wing expanse of some four inches and with a rich coloring of black and yellow more or less suffused with greenish or bluish iridescence that gives it a striking beauty as it flies leisurely about from flower to flower or stops to lay an egg upon some bush or tree. The tails are long and expanded toward the tip, their prevailing color being black with a broad splash of yellow near the end. In a general way we may say that the upper wing surface is black marked with two bands of orange-yellow, while the under surface is yellow marked with two bands of black. (_See plate, page 64._)

The Giant Swallowtail is a tropical species which is abundant throughout the Southern states and during recent years seems to have been gradually extending its northern range. It is now commonly found as far north as forty-two degrees lat.i.tude, from Nebraska eastward. In New England it is occasionally taken in Connecticut, Ma.s.sachusetts, and even in Maine, but its appearance in this region is exceptional.