But when the days have grown longer and warmer, and the trees are arrayed in their livery of green, she is in the fields bright and early, and often ere the dew has disappeared from the grass and the flowers. The most restless of beings she now is. Anon alighting upon a bush for a momentary rest, then off for a dozen or more rods, when the presence of some favorite blossom meets her quick sight and invites her to pause, which she does, but only for a second to quench her thirst. Where willows, or elms, or poplars abound, she is more frequently seen later on in May, but flying more slowly and sedately than ever before. The flowers pass unheeded. She seems in a dream, in a reverie. But all of a sudden she quickens her speed. You look for the cause. There, in the distance, another is seen, just like her in mien, some would-be suitor for her hand and affections. He enters his suit, he pleads his great love, and awaits her sweet pleasure. The answer is brief, and soon by their actions, as high up in the air they circle and circle, caressing each other with strokes of the antennæ, the story is told that his love has been requited. A brief honey-moon of two or three days and the love-scene is over, and the two settle down to the prosy realities of everyday life. The male goes back to his old-time pursuit of rifling the flowers of their honeyed treasures, whilst the female, upon whom devolves the duty of providing for the offspring whom she is never likely to see, looks scrutinizingly about for her favorite trees, the poplar, the elm, or the willow. In her selection of a tree a wonderfully keen discernment is shown, for she seldom, if ever, mistakes her plant-species. [Illustration: MOURNING-CLOAK BUTTERFLY. Larva Feeding on Willow Leaf, and Chrysalis Suspended from Twig.] When a choice has been made, no time is expended in fruitless endeavor. She proceeds at once to deposit her eggs. They are laid in a cluster round the twig, and near the petiole of a young leaf, upon which the newly-hatched larvæ are to feed. The eggs hatch inside of a week into small black spiny caterpillars which, in their early stages, are very social in their habits. Just before the final skin-moulting they separate, each caterpillar living alone, the necessity for food, which their very vigorous appetites now demand, being the impelling motive. In a state of maturity the larvæ are two inches in length. They are black, and minutely dotted with white, which gives them a greyish look. A row of brick-red spots are found down the back, and their body is armed with many black, rather long and slightly branching spines. The head is black, and roughened with small black tubercles.