Butterflies Worth Knowing Part 9

[C] "Nature Sketches in Temperate America", p. 83.

Dr. Hanc.o.c.k found that the b.u.t.terflies 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 cl.u.s.tered flower heads.

=The Olympian Orange-tip= _Synchloe olympia_

In various parts of the Southern states there is at least one other Orange-tip b.u.t.terfly 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 s.e.xes.

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.

[Ill.u.s.tration: _From a drawing by Mary E. Walker_ _See page 72_

THE TIGER SWALLOWTAIL (Reduced)]

[Ill.u.s.tration: _From a drawing by W. I. Beecroft_ _See page 83_

THE IMPORTED CABBAGE b.u.t.tERFLY Caterpillar, chrysalis, and b.u.t.terflies]

Most of the Orange-tip b.u.t.terflies 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.

_Synopsis of the Orange-tips_

_Falcate Orange-tip_ (_Synchloe genutia_, _Anthocaris genutia_ or _Euchloe genutia_). Expanse 1 2/5 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 s.e.xes with greenish black markings at base of all wings and along front margin of front wings, especially at apex. No orange patch.

THE TRIBE OF THE YELLOWS

A large proportion of our most abundant and conspicuous b.u.t.terflies belong to the Tribe of the Yellows. Sometimes it is called the Tribe of the Red-horns because the antennae of the living insects are so often red. These insects vary in size from the large Brimstones or Cloudless Sulphurs, expanding three inches, to the delicate little Dainty Sulphur, expanding scarcely an inch. The distinctive characteristics of the tribe are found in the very gradual enlargement of the joints of the antennae that form the club, and the stout palpi, the last joints of each of the latter being short.

=The Brimstone or Cloudless Sulphur= _Callidrayas eubule_

Practically all northern b.u.t.terflies are variously marked in different colors, while the b.u.t.terflies of tropical regions are commonly tinted in monotone, though often showing a splendid iridescence. One with very little experience can tell the look of a tropical b.u.t.terfly and would be likely to say at once that the Cloudless Sulphur is one of these. The upper surface of the wings of the male is a clear plain sulphur with merely the narrowest possible fringe of brown around the margin made only by the colored marginal scales. The under surface is lighter and spa.r.s.ely dotted in brown. In the females the marginal brown takes on the shape of a series of small crescents and there is a single round brown eye-spot just in front of the middle of each front wing.

While the Cloudless Sulphur is without doubt essentially a tropical species it has an extraordinary geographical range. It is extremely abundant in Mexico, Cuba, and the tropical zone in South America. It extends south even to northern Patagonia and north to New England, Wisconsin, and Nebraska.

Presumably in the tropics this species breeds continuously, one generation following another in regular succession unless interrupted by drought or other natural phenomena. In our Southern states there is more or less interruption by the winter season, so that it is commonly considered to have only two broods, the b.u.t.terflies hibernating.

Farther north there is probably only one brood in summer, and perhaps not even that in the extreme limit of its range. For there is pretty good evidence that the specimens seen in the Northern states are migrants from the south, coming singly or in scattered flocks in early summer, and if they lay eggs the b.u.t.terflies of the new generation return south in autumn. But the precise conditions are not well known and need careful observations in various localities.

The life-story of a generation of these b.u.t.terflies is much like that of the other Yellows. The eggs are laid, one in a place, on the leaflets of various species of wild senna (_Ca.s.sia_) and soon hatch into cylindrical caterpillars that devour the tender leaflets. In a few weeks the caterpillars mature and change to curious and characteristic chrysalids. The head projects in the shape of a cone and the back is so concave as to give the side view of the chrysalis a very striking appearance.

Like so many of the Yellows this b.u.t.terfly is sun-loving and social in its habits. Great numbers flock together, their large size and bright coloring rendering them very conspicuous. They often alight on the ground to sip moisture when they have been likened to beds of yellow crocuses. They also fly long distances in flocks that attract much attention. It is likely that the northward distribution takes place in summer through such migrating hosts.

_Other Sulphur b.u.t.terflies_

The Large Orange Sulphur is a closely related b.u.t.terfly of about the same size, in which the coloring is uniformly orange-yellow instead of lemon-yellow. It also belongs to the tropics, occurring in our extreme Southern states and ranging occasionally as far north as Nebraska.

The Red-barred Sulphur is another splendid b.u.t.terfly, somewhat larger than the Brimstone, which is easily distinguished by the broad reddish bar across the upper surface of the front wings. It is tropical but migrates rarely even as far north as Indiana, Illinois, and Wisconsin.

=The Dog's-head b.u.t.terfly= _Meganostoma caesonia_

The Dog's-head b.u.t.terfly furnishes one of the most remarkable examples of accidental resemblance in wing markings that can be found in the whole order of scale-winged insects. It is comparable with the skull and crossbones on the back of the death's-head moth. In the b.u.t.terfly the middle of the front wings has a broad band of yellow against a black margin on each side and the yellow outlines make an excellent silhouette of the profile of a poodle with a large black eye-spot in exactly the proper place. The females are less brightly colored than the males but they still show the dog's-head silhouette.

This is a southern species, which occasionally strays as far north as New York City, New Hamps.h.i.+re, Wisconsin, and Iowa. The larvae feed on species of Amorpha and are believed to be three-brooded in southern regions where the b.u.t.terfly occurs.

The California Dog's-head is even more beautiful than the southern species. It is remarkable for its pink and purple iridescence--a characteristic which is not common in the b.u.t.terflies of the Yellow and the White Tribes. The silhouette of the Dog's-head is less perfect than in the more eastern species, and the yellow color tones are more tinged with orange. The female is strikingly different, the wings being plain pale yellowish buff marked only with a round blackish eye-spot near the middle of each front wing and the barest suggestion of a dark line around the extreme margin.

=The Clouded Sulphur= _Eurymus philodice_

It is an interesting fact that the b.u.t.terfly which one is most likely to find in fields and along roadsides during practically all the weeks of summer has seldom if ever been noted as a destructive insect. The Clouded Sulphur is probably the commonest species in its group. There may be times when the White Cabbage b.u.t.terfly or other forms are more abundant, but the Clouded Sulphur retains its place season after season, with comparatively little noticeable variation in its numbers.

This is doubtless an ill.u.s.tration of an insect which has established such relations with its food plants and its various insect and other enemies that it remains in a fairly stable equilibrium--an example of what is often called the balance of nature.

The Clouded Sulphur is about the only medium-sized yellow b.u.t.terfly generally found in the Northeastern states. The adults may be seen from spring until autumn. They lay eggs upon clover and other plants.

These eggs hatch into small green caterpillars that feed upon the leaves and are protectively colored so they are comparatively seldom seen. When the food plant is disturbed they drop to the ground, crawling up again upon stems and leaves when the disturbance is over.

These caterpillars moult several times during their growth. When full grown they find such shelter as they are able and each spins a silken web over part of the surface. It then fastens its hind legs into this web and later spins a loop near the front end of the body. It pushes itself beneath this loop and waits for several hours before the skin breaks open along the back and is gradually shuffled off revealing the chrysalis in position. A week or two later the fully developed b.u.t.terfly emerges from the chrysalis.

These yellow b.u.t.terflies lend a distinctive charm to our summer landscapes. They are constantly to be seen fluttering from place to place, lightly visiting flowers of many kinds from which they suck the nectar, and gathering in great colonies by roadside pools where they seem to sip the moisture. There are many references to this insect in the writings of New England authors. It evidently was an especial favorite of James Russell Lowell who has often referred to it in pa.s.sages like this:

"Those old days when the balancing of a yellow b.u.t.terfly over a thistle bloom was spiritual food and lodging for a whole forenoon."

=The Orange Sulphur= _Eurymus eurytheme_

Were one able to take a Clouded Sulphur b.u.t.terfly and change the yellow to a deep orange color he could easily make a specimen that would pa.s.s for the present species. The resemblance is very remarkable and shows the close affinity between these two beautiful insects.

Like so many others of this group the Orange Sulphur is essentially a tropical species. In the eastern United States it is rarely found north of lat.i.tude forty degrees, but south of that it becomes increasingly abundant as one approaches the tropics. It occurs from the Carolinas to Texas, and over the great range in which it lives it takes on many different forms and habits. It is one of the most remarkable examples of variation in coloring exhibited by any of the b.u.t.terflies. Nearly a dozen species names have been given to its various disguises, all of which are now recognized as synonyms. In the more northern regions where it is found, only one of these forms usually occurs, but in other places bright yellow and pale white varieties are found.

The life-history of this b.u.t.terfly along lat.i.tude forty degrees is very similar to that of the Clouded Sulphur. There seem to be usually two broods and the caterpillars live upon leguminous plants, especially alfalfa, buffalo clovers, wild senna, and other species of Trifolium and Ca.s.sia. Apparently also it hibernates in both the caterpillar and the b.u.t.terfly stages.

In the extreme Southwest--as on the plains of Texas--the vegetation dries up completely in summer so that there is no succulent leaf.a.ge for the caterpillars to live upon. In such cases the insect must aestivate rather than hibernate. This species apparently succeeds in doing this by having the caterpillars go into a more or less lethargic condition in which they pa.s.s the summer. The adult b.u.t.terflies utterly disappear in June and are not seen again until early in autumn when the autumn rains have started the growth of vegetation anew. The insects then make up for lost time and produce several broods in rapid succession.

In the Imperial Valley of California this b.u.t.terfly is a serious pest to alfalfa growers. It continues to reproduce throughout a very long season, one brood following another from March until December, and in mild winters there seems sometimes to be practically no cessation of its activities. Mr. V. L. Wildermuth found that the development of a generation in breeding cages in this valley varied from twenty-two to forty-four days, the latter in cool, the former in hot weather. The stages in the first and the third broods in spring varied thus: Egg, first six days, third four days; larva, first thirty days, third twelve days; chrysalis, first eight days, third five days. In this case the first generation extended from March 15 to April 30 and the third from May 28 to June 20. After the fourth brood of b.u.t.terflies there was such an overlapping of the various stages that it was impossible to distinguish the broods.

=The Pink-edged Sulphur= _Eurymus interior_

This beautiful b.u.t.terfly was first made known to the world of science by Louis Aga.s.siz, the great naturalist who did so much to arouse a scientific interest among Americans. He found it on a famous expedition to the northern sh.o.r.es of Lake Superior, which not only served to bring to light many interesting phases of geological history but also laid the foundation for the copper mining industry which has since become so important in that region. The b.u.t.terfly thus brought to light has been found to be a characteristic northern species, occupying a rather narrow belt nearly along the fiftieth degree of lat.i.tude and extending west almost to the Pacific Coast. The species is occasionally taken as far south as the White Mountains and there are indications that in this region there are two broods a year. The male b.u.t.terflies are known at once by a beautiful pink edge on all the margins; they bear otherwise a close resemblance to our common Sulphur Yellow. The females are much lighter in color, often having no black markings on the upper surface of the hind wings.