Butterflies - The Tribe Of The Orange-tips
( Originally Published 1917 )
There is perhaps no group of butterflies whose beauty seems more fragile than that of the Orange-tip . These are delicate creatures, with slender bodies an almost gauzy wings, of a size somewhat smaller than our common white and yellow butterflies. Perhaps the most remarkable feature is the marking of the wings, the upper sides of the front pair having an orange patch near the apex and the under sides having a background of delicate whitish or yellowish green, lined and spotted with darker coloring in a very characteristic way. This peculiar marking is so significant that it has been called "flower picturing." To understand the reason for its existence one has only to watch the butterflies in their native haunts. He will find them flitting from blossom to blossom among the plants of the mustard family the Cruciferae. This is one of the most characteristic families in the plant world: the foliage for the most part is small and delicate and the flowers have a characteristic four petaled structure, being practically always of small size and generally toned in whites or yellows. When an Orange-tip is at rest upon these blossoms it merges so completely into the back-ground that it disappears from view. Should a bird chase one of these insects through the air it would see chiefly the orange tips which are so marked upon the upper side of the wing, and when the butterfly closed its wings and lighted among the flowers the orange color would instantly disappear and there would be only an almost invisible surface against the background of flower and leaf.
The adaptations of these Orange-tips to the conditions of their lives are by no means confined to this remarkable re-semblance to the flowery background. In the case of some species the whole yearly cycle has been adapted to correspond to the yearly history of the cruciferous food plant.
As is well known many species of the mustard family spring up early in the season, put forth their blossoms which quickly develop into fruits and then die down, the species being carried through until the next year by the dormant seeds. In a similar way the Orange tips feed as caterpillars upon the host plant through the spring, completing their growth before the plant dies and then changing to chrysalids which remain dormant through summer, fall, and winter and come forth as butterflies early the following spring. The insect has thus adapted itself in a most remarkable manner to the yearly history of its plant host.
The Falcate Orange-tip
The Falcate Orange-tip is about the only member of this tribe generally distributed east of the Rocky Mountains. This is a beautiful insect which is sparingly found even as far north as New England. It is more abundant throughout the Southern states, occurring south at least as far as Texas. It appears to be a good Illustration of the adaptation of its development to that of its food plants.
The eggs are laid upon leaves or stems of such spring-flowering Cruciferae as rock cress (.Arabis), and hedge mustard (Sisymbrium). On hatching the caterpillars feed upon stems, leaves, flowers, and even seed pods of these plants, becoming mature in a few weeks and changing to chrysalids under the protection of such shelter as they can find In the Northern states these chrysalids remain unchanged until the following spring when the butterflies emerge and are found upon the wing for a few weeks in May and early June.
In some southern regions at least the species is evidently double-brooded, as Dr. Holland reports that he has taken the butterflies in late autumn in the western portion of North Carolina.
This Falcate Orange-tip is one of the daintiest and most exquisite of northern butterflies. It is a prize which any collector will find joy in possessing. It is easily recognized by its general white color, which in the female is relieved only by a distinct black mark on the upper surface of the front wings and a row of marginal markings upon all the wings. The male is slightly smaller and is at once known by the orange blotch on the outer angle of the upper surface of the front wing. This outer angle projects into a distinct point which gives the species its name Falcate.
Dr. J. L. Hancock has described in a most interesting manner the way in which this Orange-tip loses itself among the flowers of rock cress. In northern Indiana he found this butterfly abundant in April at the time of the blossoming of Arabis lyrata. The butterflies would be flying about, easily seen in the air. Then they would suddenly disappear and could be found only after the most careful search. They had simply lit upon the flower heads, when the flower picturing of the under surface of the wings blended perfectly with the appearance of the clustered flower.
"The green markings of the under side of the wing," writes Dr. Hancock, "are so arranged as to divide the ground color into patches of white, which blend with or simulate perfectly the petals of the clustered flowers. The eyes of the butterfly are delicate pale green and the antennae are whitish, all of which adds to the effectiveness of the blend. The flowers of Arabis have white petals with the centre yellowish green, as is also the calyx. There is a shade of pink outside the base of the petals. All in all, the adaptation of insect to flower here displayed is one of rare exquisiteness."
Dr. Hancock found that the butterflies were able to cling on the flowers during strong winds very persistently, so that even when a storm blew across the sand dunes they were likely to remain in position. They also have the instinct to rest very quietly after they have lit upon the clustered flower heads.
The Olympian Orange tip
In various parts of the Southern states there is at least one other Orange-tip butterfly which is found occasionally in connection with the Falcate Orange-tip. It was named Olympia many years ago by William H. Edwards. It is a delicate white species marked with black and yellow very lightly both above and below, the yellow showing only on the under side of the hind wings and that part of the front wing which is exposed when the insect is at rest. Strictly speaking, this is not an Orange-tip because the orange color is lacking in both sexes.
This is rather a rare species which occurs occasionally from the Atlantic states to the Great Plains south of a line drawn from northern Maryland to northern Missouri. Like its allies the larvae feed upon various cruciferous plants, the hedge mustard being one of these and the adults visit the flowers of the same family. They doubtless have habits similar to those of the Falcate Orange-tip, and the extreme delicacy of color must render them practically invisible when resting upon the small white flowers of most crucifers.
Most of the Orange-tip butterflies are found on the Pacific Slope, ranging from Alaska southward, several of them being especially abundant in the western mountain regions. About eight species are recognized as belonging to our fauna, some of which have several well-marked varieties.
Synapsis of the Orange-tips
Falcate Orange tip (Synchloe genutia, Anthocaris genutia or Euehloe genutia). Expanse 1* inches. Tips of front wings projecting in a hooked angle. Orange blotch on upper surface near tip in male, absent in female.
Olympian Orange tip (Synchloe olympia, Euchloe olympia or Anthocaris olympia). Expanse 1 1/2 inches. Wings white above in both sexes with greenish black markings at base of all wings and along front margin of front wings, especially at apex. No orange patch.