Butterflies Worth Knowing Part 10

=The Black-bordered Yellow= _Eurema nicippe_

This is essentially a tropical b.u.t.terfly which has spread out over most of our Southern states where it is abundant and widely distributed. It adds a distinct touch of color and life to many landscapes when the b.u.t.terflies swarm by thousands upon clover blossoms and other low vegetation. The eggs are laid upon the leaves of clover and more especially upon some common species of Ca.s.sia, such as wild senna. Each egg soon hatches into a small greenish cylindrical worm, colored and striped in such a way that as it rests upon the leaf it is easily overlooked. This larva develops rapidly and soon becomes about an inch and a quarter long, being rather slender and fairly smooth. It now spins a bit of silk upon a twig or some similar support and also the frailest sort of a silken loop to pa.s.s around its back.

It now entangles its hind feet in the bit of silk and soon casts off its last caterpillar skin, emerging as a curious looking chrysalis about three quarters of an inch long with a remarkable pointed projection on the front of the head. When seen through a hand lens this pointed projection and the well-developed characteristic wing sheaths give the chrysalis a remarkable resemblance to some of the twig hoppers or Membracids. The colors vary considerably with the surroundings but are commonly toned in various shades of green and yellow brown.

A little later each chrysalis breaks open to disclose one of the beautiful b.u.t.terflies.

The conditions under which this b.u.t.terfly lives at the limit of its northern range are not well determined. It is probable that many of those seen here have flown from considerably farther south, and that these migrants lay eggs from which a brood of b.u.t.terflies develops, these native born appearing late in summer. Presumably the latter hibernate, but whether they can do this successfully under the rigorous conditions of our northern winters has never been determined.

In fact, Scudder wrote some years ago that no caterpillars had ever been found in New England. Here is an interesting opportunity for some young observer to make a real contribution to science.

=The Little Sulphur= _Eurema lisa_

Were one to imagine a Clouded Sulphur b.u.t.terfly reduced to half its usual size and built with a corresponding delicacy of structure, one would have a pretty good idea of the beautiful little creature called by the above name. I well remember in my college days taking what was probably the first of these b.u.t.terflies ever collected in the region of our Michigan college. It was a prize that very likely had wandered north from Indiana but which served to add much glory to the little collection in which I took such pride, for this is essentially a southern species. In many regions of the South it is so abundant that it can be taken by any one. It ranges from coast to coast and extends south into the tropics. In the eastern region it is found from southern Wisconsin to southern New England, occurring sparingly and locally in various places along the line thus indicated.

The food plant of the species is chiefly wild senna or other kinds of Ca.s.sia. The mother b.u.t.terflies deposit the eggs singly on leaves or stems, generally on the small leaflets of the compound leaf. Less than a week later each egg hatches into a cylindrical greenish caterpillar that feeds upon the leaflets in a characteristic fashion. Instead of devouring the blade from the margin inward it gnaws narrow strips between the smaller veins. When not feeding, the caterpillars protect themselves from observation by birds or other enemies by resting motionless along the stem of the leaflet or else along the midrib on the under side. As is well known the leaflets of Ca.s.sia, like other leguminous plants, close at night. It is probably on this account that these caterpillars feed chiefly by day. The general green color of the skin and the straight stripe along the side help to make this caterpillar very inconspicuous when it is at rest.

When full grown the caterpillar reaches a length of three quarters of an inch. It now finds some bit of shelter on which it spins a bit of flat web and a silken loop to hold it in place as it becomes a chrysalis. It then changes and remains quiescent for ten days or more when it emerges as the dainty b.u.t.terfly.

Notwithstanding its abundance and its successive broods its life-history is none too completely worked out. There is still opportunity for careful observations upon the way in which it pa.s.ses the winter in various parts of its range. While in the South it apparently hibernates as an adult, this fact is not certain in the more northern localities.

Notwithstanding its diminutive size this b.u.t.terfly has been known to swarm in such enormous numbers as to seem a veritable cloud. The most notable record of this has been quoted by Scudder in connection with a swarm that invaded the Bermuda Islands, in 1874, on the first day of October. It was described in these words:

"Early in the morning several persons living on the north side of the main island perceived, as they thought, a cloud coming over from the northwest, which drew nearer and nearer to the sh.o.r.e, on reaching which it divided into two parts, one of which went eastward and the other westward, gradually falling upon the land. They were not long in ascertaining that what they had taken for a cloud was an immense concourse of small yellow b.u.t.terflies, which flitted about all the open gra.s.sy patches in a lazy manner, as if fatigued after their long voyage over the deep. Fishermen out near the reefs, some few miles to the north of the islands very early that morning, stated that numbers of these insects fell upon their boats, literally covering them."

As is the case with so many of the related yellow b.u.t.terflies there is an albino variety of this species. It has been given the variety name _alba_ although it is really a pale yellow rather than a true albino form.

=The Dainty Sulphur= _Nathalis iole_

While the Little Sulphur b.u.t.terfly seems about as delicate a creature as one could ask to see, it loses that distinction when it is compared with the still smaller Dainty Sulphur. The latter expands scarcely an inch when its wings are stretched apart, and its slender body and antennae help to give the suggestion of extreme delicacy. There is more marking of black upon the sulphur-yellow wings than is the case with the larger form, the upper portion of the front wings showing only a broad yellow band upon a background of darker color. The under wings are nearly all yellow.

_Synopsis of the Yellows_

_Brimstone_ or _Cloudless Sulphur_ (_Callidryas eubule_ or _Catopsilia eubule_). Expanse 2 1/2 inches. Upper surface of male clear, light, sulphur yellow. Female with a brown spot in front of middle of each front wing and a narrow brown margin on all the wings.

Under surface deeper yellow with spa.r.s.ely scattered brownish dots.

_Red-barred Sulphur_ (_Callidryas philea_ or _Catopsilia philea_).

Expanse 3 inches. Easily known by the reddish orange bars on the sulphur-yellow wings.

_Large Orange Sulphur_ (_Callidryas agarithe_ or _Catopsilia agarithe_). Expanse 2 1/2 inches. Distinguished at once by its uniform orange-yellow color.

_Dog's-head b.u.t.terfly_ (_Zerene caesonia_, _Colias caesonia_ or _Meganostoma caesonia_). Expanse 2 1/4 inches. Upper surface yellow with black inner and outer borders on front wings and black outer border on hind wings. The black and yellow of each front wing so combined as to make a distinct dog's head with black eye.

_Clouded Sulphur_ (_Eurymus philodice_ or _Colias philodice_). Expanse 2 inches. Upper surface sulphur yellow with blackish borders, the yellow brighter in the male than in the female. Male with line between yellow and black distinct, a black spot just in front of the middle of each front wing and an orange spot near the middle of each hind wing.

Under surface of male deeper yellow, with spots as on the upper surface but without black margin, and with a row of sub-marginal brownish dots on each wing. Female with upper surface more generally suffused between marginal mark and the yellow part with more or less duskiness both above and below. Spots on each wing much as in male. In the white form of the female (_pallidice_) the yellow is replaced by white.

_Pink-edged Sulphur_ (_Eurymus interior_). At once distinguishable from _philodice_ by the narrow pink edge of all the wings, showing both from above and from below, slightly smaller as a rule.

_Orange Sulphur_ (_Eurymus eurytheme_ or _Colias eurytheme_). Expanse 2 1/4 inches. Much like Clouded Sulphur in markings except that prevailing color-tone is orange yellow.

_Black-bordered Sulphur_ (_Eurema nicippe_, _Xanthidia nicippe_ or _Terias nicippe_). Expanse 2 inches. Upper surface of wings bright orange with a small black dash in front of the middle of each front wing and a broad black border on all the wings. In the females the borders are interrupted at the rear. Under surface slightly brownish yellow, minutely striated and clouded when exposed when the b.u.t.terfly alights.

_Little Sulphur_ (_Eurema euterpe_, _Eurema lisa_, _Xanthidia lisa_ or _Terias lisa_). Expanse 1 inch. Easily known by its small size and delicate structure. Upper surface of wings yellow with distinct black borders. Under surface yellow with indistinct spots.

_Dainty Sulphur_ (_Nathalis iole_). Expanse 1 inch. Easily known by its small size and narrow yellow wings with black bars across the outer angles and black bands across the back border of the front wings and the front border of the hind wings.

THE NYMPHS

FAMILY _Nymphalidae_

A large proportion of our most familiar b.u.t.terflies belongs to this family. The Fritillaries, the Angle-wings, the Sovereigns, and the Emperors are tribes in which practically all the species are of medium or large size. The Crescent-spots include a few which are rather small.

The combinations of characters by which the Nymph family is distinguished are these: Front legs dwarfed into lappets; scaly antennae; veins of fore wings not swollen at base; wings of normal shape, not much longer than wide. Larvae cylindrical, but varying greatly in form, color, and skin coverings. Chrysalids angular in most species, in others rounded.

The stories of the lives of the many members of this family vary considerably, as one would expect from their variety and numbers. We may take, however, the life of the familiar Antiopa or Mourning Cloak as typical of the group. Briefly summarized, its story may thus be told:

During sunny days in spring one may often see a beautiful purple-back b.u.t.terfly, having a cream-colored border along the outer margin of its wings, flying leisurely about, in the vicinity of woods and in the open fields. This insect is called the Antiopa or Mourning Cloak; it is represented natural size in plate opposite page 145. It has pa.s.sed the winter in this adult condition, having found shelter in some retreat where it is not directly exposed to the storm and stress of the weather.

When the leaves of the elm, willow, and poplar trees are nearly expanded, these b.u.t.terflies deposit their eggs upon the twigs. These eggs are laid in cl.u.s.ters encircling the twigs, there being twenty or more in each cl.u.s.ter. In the act of oviposition, the b.u.t.terfly keeps her wings spread out, moving the body and abdomen about as the placing of the eggs necessitates.

About two weeks after the cl.u.s.ters of eggs are thus laid upon the twigs of the food plant, they hatch into small blackish caterpillars, each emerging from the egg sh.e.l.l through a small hole that it eats out of the upper surface. They thus enter upon the second stage in their life-history--the larva or caterpillar stage. As soon as hatched, they crawl to the nearest leaf upon which they range themselves side by side, with their heads toward the margin of the leaf. They feed in this position, nibbling at the green surface of the leaf-blade and leaving the network of veins untouched.

[Ill.u.s.tration: _See page 76_

THE ZEBRA SWALLOWTAIL Summer form: upper surface, above; under surface, below]

[Ill.u.s.tration: _From a drawing by Mary E. Walker_ _See Page 101_

THE CLOUDED SULPHUR b.u.t.tERFLY Caterpillar and b.u.t.terfly on red clover plant. (Reduced)]

[Ill.u.s.tration: _From a drawing by Mary E. Walker_ _See page 76_

ZEBRA SWALLOWTAILS Visiting blossoming branches of the pawpaw tree. (Reduced)]

[Ill.u.s.tration: _See pages 97-115_

SOME OF THE TRIBE OF YELLOWS upper surfaces at left; under surfaces at right

(1) The Black-bordered Yellow--male; (2) the Clouded Sulphur--male; (3) the Orange Sulphur--female; (4) the Dog's-head--male]