Butterflies - The Tribe Of The Emperors
( Originally Published 1917 )
The members of this small group are distinguished from the closely related Sovereigns by the tailed hind wings in one species, by the eye-spots on the upper surface of the wings of the others, and by the fact that on the club of the antennae there are three instead of four longitudinal ridges. There is also a distinction in the arrangement of the veins of the hind wings.
This tribe is represented in our northern fauna by only two genera. In the genus Chlorippe the antennae are as long as the front wings are wide. In the genus Anoea the antennae are much shorter than the width of the front wings. Only two species of the former and one of the latter are sufficiently abundant to be considered here.
The Goatweed Emperor
Comparatively few butterflies are confined so closely to the valley of the Mississippi River as the Goatweed Emperor. From southern Illinois south to the Gulf this insect is rather abundant in many localities where its food plant, the goatweed, is common. The life-history of the insect was carefully studied by Dr. C. V. Riley, and one of the best accounts was published in one of his early reports on the insects of Missouri. The excellent illustrations in that article first made the species familiar to many students.
Briefly summarized, the life-history runs something like this: the butterflies hibernate, coming forth in spring and visiting various spring and early summer flowers. The females deposit eggs singly upon the leaves of the young goatweed plants. In a week or less each egg hatches into a little caterpillar that feeds upon the tip of the leaf leaving the midrib and covering it with silk so that it may serve as a resting perch. Later each makes an excellent tent for itself by bending over and binding together the opposite margins of a leaf.* This bit of work is cleverly done, a hole being left at each end so that there is good ventilation and an opportunity for the cater-pillar to go in and out. Quite frequently the nest is also lined with more or less silken webbing. This tent is used as a refuge from the heat of the sun and doubtless serves also in concealing the caterpillar from its many enemies. The larva goes out to neighboring leaves when it wishes to. feed and only occasionally eats up the leaf of which its tent is made. When this is done it must of course find another home.
After some weeks of this sheltered existence the caterpillar is ready to change to a chrysalis. It leaves the tent and commonly attaches a bit of silken web to the under side of a leaf or branch of its food plant or some other kind of shelter. Here it changes to a chrysalis, to emerge a little later as the beautiful burnt-orange butterfly. There are said to be two broods each season, in some regions, although in others there seems to be but one. The butterflies hibernate in hollow trees or in such other shelters as they may find.
The full-grown caterpillar (a) is an inch and a half long and of a general grayish color, dotted thickly with slightly elevated points. The chrysalis (b) is suggestive of that construct of the Monarch buterfly. It is light green covered with whitish granules.
The adult buttery is remarkable for the falcate shape of the outer margin of each front wing and the broad tail at the hind outer angle of each hind wing. In the male the upper surface of all the wings is of a dark orange tone, with a rather narrow brown marginal marking. In the female this marginal band is broader and is nearly paralleled by another narrower band a little nearer the body. In bright sunshine there is a distinct purplish red iridescence over practically the whole upper surface. The under side of both wings is of a color to suggest a dead brown leaf, with a purplish iridescence in certain angles of light.
The Gray Emperor
This very distinctive medium sized butterfly is found in the Southern states] at least as far west as the Mississippi Valley. It extend north to Indiana and Ohio and probably occurs quite generally from Ohio eastward. This species is distinguished by the general gray brown or olive brown coloring of é wing surfaces, heavily marked with a much darker dusky brown and with many irregular white spots as well as one large eye spot on each front wing near the border, and a row of seven more or less distinct eye spots near, the border of each hind wing.
Like the Tawny Emperor this species feeds in the larval state upon the leaves of hackberry. In Missouri the butterflies appear in June. A little later they lay eggs upon the under side of the hackberry leaves, commonly one in a place but sometimes several side by side. A few days later these eggs hatch into little yellow caterpillars that feed upon the leaves for about a month when they become full grown. They are then a little more than an inch long, of a general light green color with yellow spots along the middle of the back and three yellow lines along each side. The head has a pair of curious antlers much like those of the caterpillar of the Tawny Emperor. These caterpillars now spin a bit of silken web on the under side of the leaf or twig. They attach their hind legs into this web and hang downward for a day or two, before casting the last larval skin and changing to chrysalids. They change again to butterflies which are seen upon the wing early in August. These butterflies Iay eggs in turn on the hackberry leaves, the eggs soon hatching into small caterpillars which according to Riley's observations are less active than those of the earlier brood. These cater-pillars feed for a few weeks until they become nearly half grown and have passed their second or possibly their third moult. They now stop eating and get ready for a long fast through the winter. Apparently some of them at least attach themselves to the under side of the hack-berry leaves and turn to a brownish color, remaining upon the leaves until the latter fall to the ground and presumably hibernating in the shelter thus provided. Whether or not all of the caterpillars have this rather curious habit seems to be doubtful. It has been suggested that some of them find shelter within the crevices in the rough bark of the tree. At any rate, the caterpillars remain in a sort of stupor until the following spring. Then they awaken, climb up the trees or bushes, and begin feeding upon the young leaves. They continue this until they become full grown in May when they change to chrysalides, to emerge the first brood of butterflies the following month. Many of the caterpillars make a sort of nest for themselves by spinning a web of silk upon the under surface of the leaf and drawing together slightly the outer edges.
As is the case with so many other butterflies that hibernate as caterpillars, apparently the species is only partially double-brooded. Some of the earlier caterpillars become lethargic when half grown and remain in that condition throughout the later weeks of summer and all through the fall and winter.
The Tawny Emperor
Chlorippe clyton This handsome butterfly is easily distinguished from the Gray Emperor by the general reddish color of the wings which are thickly marked with bands and eye-spots of darker brown or black. The eye-spots are especially marked on the hind wing, there being a row of five of these on each hind wing in both sexes. The females are decidedly larger than the male and generally of a distinctly lighter color.
This butterfly is a southern species found more or less abundantly from southern New York to northern Florida and across the country to a line drawn from Iowa to Texas It seems to be more common in the Mississippi Valley than in other regions and its life-history was first thoroughly worked out in Missouri and published in one of Riley's classic reports on the insects of that state. It has since been studied by Edwards and others, but even now there seems to be some uncertainty in regard to many points in its development, notably the number of broods in different localities and the habits of the larvae when preparing for hibernation.
The principal points in the life-history of the species may be outlined as follows: some time in July the eggs are laid on the leaves of hackberry in dense clusters, each of which may contain from two hundred to five hundred eggs. These are usually deposited in two or more layers, one upon another. A little more than a week later these eggs hatch, each caterpillar eating through one end in a way to cut out the rim of a tiny cap which is pushed up as the larva escapes. The whole brood emerges at practically the same time and collects upon one or more leaves where they begin to feed upon the succulent green tissues. Like so many caterpillars that feed in companies each spins a silken thread wherever it goes.
The little larvae remain together until after the third moult, at which time they are about half grown. In the more northern regions where they are found they are now likely to scatter about in search of quarters for hibernation. Having found suitable shelter, they remain through the winter to come forth early the following spring and feed upon the developing leaves of the hackberry trees. They continue to do this for a few weeks before they become full grown. They are then smooth-bodied, greenish worms about an inch and a half long, striped longitudinally in yellow and brown. The hind end of the body is forked in a curious fashion and the head is even more remarkable for the strange pair of tiny antlers projecting from it.
These full-grown caterpillars soon change to pale green chrysalids, lightly striped with longitudinal lines of yellow, with a distinctly pointed head. From these chrysalids butterflies emerge early in summer.
Evidently in the more Southern states there are two broods of these butterflies each year but there is great need of more precise knowledge in regard to them.
As is the case with so many other butterflies there is a dimorphic form, called ocellata, in which the outer half of the hind wing is very dark brown, with the eye-spot showing as black with red-brown circles.
Synopsis of the Emperors
Goatweed Emperor (Anoea andria or Pyrrhanea andria). Expanse 2 1/2 inches. Front outer angle of each front wing projecting into a falcate tip. Rear outer angle of each hind wing projecting into a distinct tail. General color burnt-orange with darker marginal bands, and in the female on the upper surface other sub-marginal markings.
Gray Emperor (Chlorippe celtis). Expanse 2 inches. General color grayish brown with numerous markings of white and blackish. A distinct brown eye-spot on the upper surface of each front wing near the outer hind angle.
Tawny Emperor (Chlorippe clyton). Expanse 2 inches. General color tawny brown with markings of black and yellowish white. No distinct eye-spot on upper surface of front wings.