The perfect insect emerges in about three weeks after the change to the chrysalis; and may be looked for from July to the end of the summer. This period may be regarded as the best time in which to hunt for _Rhamni_, but it is to be noted that this butterfly makes its appearance during all months of the year, even though it is single-brooded. A large number seem to hybernate, and their winter sleep is so light that the welcome rays of the sun on a mild day, even during the bleak months of November to February, will often call them out from their hiding places. Then, as a rule, the hybernating butterflies do not live long after depositing their eggs for the future brood; but the Brimstone often lives on till its offspring have themselves attained the perfect state, so that it is possible to capture the insects of two different years both on the same day. In such a case it is generally easy to distinguish between the two, for the newly emerged specimens are beautifully bright and fresh in colour, while those of the previous year are more or less faded and worn, their wings being often semi-transparent through the loss of scales, and frequently disfigured by the stains of mildew. CHAPTER XIII _THE FRITILLARIES, VANESSAS, AND THE PURPLE EMPEROR_ Family--NYMPHALIDAE We now come to a rather large family, which contains some of our largest and most brilliant butterflies. Some of them display the most gaudy colours, and others exhibit patches of a beautiful metallic lustre. If you were to see all the members of this family side by side, they might strike you as being so varied in their appearance that you would wonder why they are all placed in one family group. But, were you to see, in addition to the perfect insects, all their larvae and chrysalides, the reason would be made clear at once, for these earlier stages are seen to resemble each other in certain points at the very first glance. The former are all provided with peculiar spines, and the latter are all more or less angular, and are all suspended to a silken carpet by means of hooks at the tip of the abdomen, and have no belt as we have observed in the case of the _Pieridae_. The perfect insects, too, although so varied in colouring, are alike in that they have only four walking legs, the first pair being so imperfectly developed as to be useless for this purpose. This family includes the Fritillaries and the Vanessas. _The Small Pearl-bordered Fritillary_ (_Argynnis Selene_) The interesting group of butterflies known as the Fritillaries vary considerably in size, but are remarkably uniform in the ground colour of the wings, which, in all cases, is a rich golden or sienna brown; and this ground is chequered with darker colours in such a manner as to remind one of the petals of the wild flower known as the Snake's Head or Fritillary--hence the popular name of the group.