Sometimes this butterfly is known as the Clouded Sulphur. It appears in the same places, and at the same time of the year, as the “clouded yellow,” but is hardly ever quite as common. Generally, indeed, you may see ten or twelve “clouded yellows” to one Pale Clouded Yellow. You can easily tell it by its much paler colour, for its wings are quite light yellow instead of rich orange, while sometimes one meets with a Pale Clouded Yellow which is really almost white. And, besides that, the black border of the upper wings, instead of being nearly the same width all the way along, is very broad at the top and very narrow at the bottom, while even in the male it is marked with several yellow spots. This pretty butterfly is quite a seaside insect, and sometimes it may be seen fluttering over the waves a long way out from the shore. Indeed, there seems to be very little doubt that now and then it flies right across the Straits of Dover, and reaches this country from France! The caterpillar of the Pale Clouded Yellow is olive-green in colour, sprinkled with black dots, and with two yellow lines along its back and another on each side. It feeds on clovers and trefoils. [Illustration: PLATE XIV 1. Swallow-tail 2. Swallow-tail Caterpillar] PLATE XIV THE SWALLOW-TAIL (1 and 2) This is the finest of all our British butterflies, and a most beautiful creature it is as it flits to and fro in the sunshine. But I am afraid that you are not very likely to see it alive, for it is only found in the fens of Norfolk and Cambridgeshire, while even there it is not as common as it used to be. But if ever you spend a summer holiday in the Norfolk Broads you may, perhaps, see one of these lovely butterflies flying swiftly past you. The caterpillar is almost as handsome as the butterfly. It is bright green in colour, with velvety-black rings, which are spotted with red. And just behind its head it has an odd little forked organ, from which it pours out a drop of liquid when it is frightened. This liquid has a very nasty smell, and no doubt it prevents birds from feeding upon the caterpillar. This caterpillar feeds upon hog’s fennel, wild carrot, and marsh milk-parsley. When it has reached its full size it climbs up the stem of a reed, fastens itself to it by spinning a kind of silken belt round its body, and turns into a yellowish-green chrysalis, from which the butterfly appears during the following summer. PLATE XV THE ORANGE TIP (1 and 2)