PREFACE.
India, the land of sunshine, is a land of Butterflies; for, though in the arid plains of the north insect-life languishes during the dry months, it revives marvellously when the periodic rains set in; and in the moister parts of the country, especially to the east and south, and in the warm valleys of the hilly regions, the amazing numbers of Butterflies and other beautiful insects cannot but strike the most unobservant. In one of his charming essays on tropical nature, Professor A. R. Wallace has remarked that, although in tropical countries individual flowers attain to a size and brilliancy of colouring unknown in temperate climates, it is merely in the individual flower, and not in general effect, that the products of tropical climes excel. There is nothing in tropical landscapes, for instance, that can compare with the heather and gorse of our own country, or with the gorgeous carpeting of the alpine valleys, ever moist with the melting snows. But in insect-life it is otherwise; both in size and beauty of individuals, and in prolific luxuriance of numbers, the tropics easily bear off the palm; the largest and most beautiful of European Butterflies sink into insignificance beside the Ornithoptera, Morpho and Thaumantis of the tropics; while, perhaps, few sights in nature are more strangely beautiful to the traveller in these Eastern valleys than the patches of damp sand which may be found in torrent-beds in the forests literally carpeted with Butterflies of every hue, closely packed together, busily inbibing the moisture from the sand, and, again, as startled by the approach of an intruder, they rise expanding into a cloud of gorgeous colours of every hue. The difficulty in securing rare species is, in such localities, literally the difficulty of singling them out of a crowd.
The large size, the quaint shapes, and the dazzling brilliancy of the colouring of many of the Indian Butterflies have made them favourite objects of observation and often of collection; but, though collections are frequently made or purchased, comparatively little has been done here towards investigating the life-history of these beautiful creatures, or towards improving the opportunities offered by such a study of gaining light on the scientific questions and problems of zoology.
The study of Entomolgy is not merely an interesting recreation for those who can find leisure and opportunity to pursue it, but, even when restricted to Butterflies only, it offers a field for scientific enquiry of the highest importance, in connection especially with the origin of species and other cognate questions. Putting aside the various stages of egg, caterpillar, and chrysalis, through which all Butterflies pass, and in which opportunities for study are ample, the perfect insect, as it emerges from the chrysalis, exhibits variations at least as numerous and important as those of other classes of living organisms, while the short duration of its life, and the quickly succeeding generations, offer facilities for tracing the course of such variations, and thus deducing the causes which govern them, perhaps unrivalled in the whole field of nature. These variations, though possibly traceable ultimately to the same causes, may be grouped under several heads. It must not be forgotten that variety is in a certain sense universal, for no two individuals are really absolutely alike; but numerous individuals are to be found so closely resembling each other that, to the naked eye, no difference is traceable; or, if traceable, the differences are so slight as to leave no room for doubt, even if other evidence were wanting, that the individuals are derived from the same parental stock; or, in other words, belong to the same species. It this close similarity of individuals were constant in each species there would be no
