The Gray Emperor
Chlorippe celtis
This very distinctive medium-sized butterfly is found in the Southern states at least as far west as the Mississippi Valley. It extends 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 the 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 lay 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 caterpillars 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 hackberry 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 chrysalids, to emerge as 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.