A collection of insects is to the true naturalist what a collection of medals is to the accurate student of history. The mere collector, who looks only to the shining wings of the one, or the green rust of the other, derives little knowledge from his pursuit. But the cabinet of the naturalist becomes rich in the most interesting subjects of contemplation, when he regards it in the genuine spirit of scientific inquiry. What, for instance, can be so delightful as to examine the wonderful variety of structure in this portion of the creation; and, above all, to trace the beautiful gradations by which one species runs into another? Their differences are so minute, that an unpractised eye would proclaim their identity; and yet, when the species are separated, and not very distantly, they become visible even to the common observer. It is in examinations such as these that the naturalist finds a delight of the highest order. While it is thus one of the legitimate objects of his study to attend to minute differences of structure, form, and colouring, he is not less interested in the investigation of habits and economy; and in this respect the insect world is inexhaustibly rich. We find herein examples of instinct to parallel those of all the larger animals, whether they are solitary or social; and innumerable others besides, altogether unlike those manifested in the superior departments of animated nature. These instincts have various directions, and are developed in a more or less striking manner to our senses, according to the force of the motive by which they are governed. Some of their instincts have for their object the preservation of insects from external attack; some have reference to procuring food, and involve many remarkable stratagems; some direct their social economy, and regulate the condition under which they live together either in monarchies or republics, their colonizations, and their migrations; but the most powerful instinct which belongs to insects has regard to the preservation of their species. We find, accordingly, that as the necessity for this preservation is of the utmost importance in the economy of nature, so for this especial object many insects, whose offspring, whether in the egg or the larva state, are peculiarly exposed to danger, are endued with an almost miraculous foresight, and with an ingenuity, perseverance, and unconquerable industry, for the purpose of avoiding those dangers, which are not to be paralleled even by the most singular efforts of human contrivance. The same ingenuity which is employed for protecting either eggs, or caterpillars and grubs, or pupæ and chrysalides, is also exercised by many insects for their own preservation against the changes of temperature to which they are exposed, or against their natural enemies. Many species employ those contrivances during the period of their hibernation, or winter sleep. For all these purposes some dig holes in the earth, and form them into cells; others build nests of extraneous substances, such as bits of wood and leaves; others roll up leaves into cases, which they close with the most curious art; others build a house of mud, and line it with the cotton of trees, or the petals of the most delicate flowers; others construct cells, of secretions from their own bodies; others form cocoons, in which they undergo their transformation; and others dig subterraneous galleries, which, in their complexity of arrangement, in solidity, and in complete adaptation to their purposes, vie with the cities of civilised man. The contrivances by which insects effect these objects have been accurately observed and minutely described, by patient and philosophical inquirers, who knew that such employments of the instinct with which each species is endowed by its Creator offered the most valuable and instructive lessons, and opened to them a wide field of the most delightful study. The construction of their habitations is certainly among the most remarkable peculiarities in the economy of insects; and it is of this subject that we propose to treat under the general name, which is sufficiently applicable to our purpose, of Insect Architecture.