Butterflies - The Tribe Of The Yellows Continued
( Originally Published 1917 )
The Black bordered
Yellow Eurema nicippe
This is essentially a tropical butterfly 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 butterflies 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 Cassia, 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 pass 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 butterflies.
The conditions under which this butterfly 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 butterflies 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
Were one to imagine a Clouded Sulphur butterfly 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 butterflies 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 Cassia. The mother butterflies 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 Cassia, 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 Ioop 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 butterfly.
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 passes 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 butterfly 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 shore, 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 butter-flies, which flitted about all the open grassy 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 butter-flies 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
While the Little Sulphur butterfly 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 21 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 sparsely 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 Butterfly (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 butterfly 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.