The caterpillar of this butterfly is a little apple-green creature, with a darker stripe edged with white running along its back, and another along each of its sides. It feeds upon grass, and when it is fully fed it spins a kind of silken belt round a grass-stem, fastens itself to it with its head hanging downwards, and then changes into a bright green chrysalis with a short purple stripe, bordered with white, on each side. [Illustration: PLATE VIII 1. Green Hair Streak 2. Purple Hair Streak] PLATE VIII THE GREEN HAIR-STREAK (1) The Hair-streaks are pretty little butterflies which you can very easily tell by sight. For, in the first place, they always have a pale streak, or a row of little white dots, scarcely thicker than a hair, running across the lower surface of the wings. That is why they are called “Hair-streaks.” And, in the second place, the hind-wings have a pair of little tails, something like those of the swallow-tail butterfly, only of course very much smaller. Five different kinds of these butterflies are found in the British Islands, but only two of them are at all common. For the Green Hair-streak you should look on heaths, in open spaces in woods, on grassy banks by the roadside, and in other places in which brambles grow. You can easily tell it from all the other Hair-streaks by the bright green colour of its lower surface, and also by its small size, for it only measures about an inch across its outspread wings. The caterpillar, which is light green or greenish-yellow in colour, with a row of triangular yellow spots running along each side, feeds on bramble shoots and blossoms. You may find it in July, and the butterfly makes its appearance in May and June, and sometimes again in August. PLATE VIII THE PURPLE HAIR-STREAK (2) This is the commonest of the Hair-streak butterflies, for there is scarcely a wood in which oak trees grow in which you may not find it. But it is quite easy to walk through a wood without seeing it, for it nearly always flies at some little height from the ground. And besides this it is very fond of sitting on leaves and basking in the sun, not moving for some little time unless it is disturbed. The male is much handsomer than the female, for the whole upper surface of the wings, except just the margin, is of the richest possible purple, which seems to shine and glisten in the light, while in his mate there is only a purple blotch in the middle of the wings. The caterpillar of this butterfly is a most odd little creature, and really looks much more like a little fat slug. It is reddish-brown in colour, with a number of black marks upon its back. You may sometimes find it clinging to oak leaves, on which it feeds. When it is fully grown it generally descends to the ground, buries itself just below the surface, and turns into a fat little brown chrysalis, from which the butterfly appears in July. [Illustration: PLATE IX 1. Small Copper 2. Common Blue] PLATE IX THE SMALL COPPER (1)