Each species of Termites consists of several distinct orders, or castes, which live together, and constitute populous, organised communities. They inhabit structures, known as 'Termitaria,' consisting of mounds or hillocks, some of which are 'five feet high, and are formed of particles of earth, worked into a material as hard as stone.' The Termitarium has no external aperture for ingress or egress, as far as can be seen, the entrance being placed at some distance, and connected with the central building by means of covered ways and galleries. Each Termitarium is composed of 'a vast number of chambers and irregular intercommunicating galleries, built up with particles of earth or vegetable matter, cemented together with the saliva of the insects.' Many of the very large hillocks are the work of many distinct species, each of which uses materials differently compacted, and keeps to its own portion of the tumulus.'

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A family of Termites consists of a king and queen, of the workers, and of the soldiers. The royal couple are the parents of the colony, and 'are always kept together, closely guarded by a detachment of workers, in a large chamber in the very heart of the hive, surrounded by much stronger walls than the other cells. They are both wingless, and immensely larger than the workers and soldiers. The queen, when in her chamber, is always found in a gravid condition, her abdomen enormously distended with eggs, which as fast as they come forth, are conveyed by a relay of workers in their mouths from the royal chamber to the minor cells dispersed through the hive.'

At the beginning of the rainy season a number of winged males and females are produced, which, when they arrive at maturity, leave the hive, and fly abroad. They then shed their wings (a special provision for this existing in a natural seam running across the root of the wing and dividing the nervures); they pair, and then become the kings and queens of future colonies.

The workers and the soldiers are distinct from the moment of their emergence from the egg, and they do not acquire their special characteristics in consequence of any difference of food or treatment. Both are wingless, and they differ solely in the armature of the head. The duties of the workers are to 'build, make covered roads, nurse the young brood from the egg upwards, take care of the king and queen, who are the progenitors of the whole colony, and secure the exit of the males and females, when they acquire wings, and fly out to pair and disseminate the race.' The duties of the soldiers are to defend the community from all attacks which may be made

upon its peace, for which purpose the mandibles are greatly developed.

It may well be admitted, that in such organised communities as those of the Termites, we have the highest development of Insect-life yet known to us. The principle of the division of labour is carried out to its fullest extent-much further, indeed, than is possible amongst human beings-since the perfection of the greater number of the individuals which compose the community-as organisms-is sacrificed in order to secure the fulfilment of the duties which are necessary for the existence and welfare of the whole. Even the task of petuating the species and of giving origin to fresh colonies is entirely left to one class of the community, the defence and protection of which is the special object and care of the remainder. No higher development could well be imagined amongst creatures devoid of the higher psychical endowments, and it is worthy of note that at least three distinct and independent families of Insects have attained to this stage, namely, the Termites, the Bees, and the true Ants.

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SUB-CLASS III. HOLOMETABOLA.-Metamorphosis complete; the larva, pupa, and imago differing greatly from one another in external appearance. The larva vermiform, and the pupa quiescent.

ORDER VII. APHANIPTERA.-Wings rudimentary, in the form of plates, situated on the mesothorax and metathorax. Mouth suctorial. Metamorphosis complete.

This order comprises the Fleas (Pulicidae), most of which are parasitic upon different animals. The larva of the com

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Fig. 66.-Diptera. 1. Tabanus cinctus, the belted Breeze-fly. 2. The organs
of the mouth magnified.

mon Flea is an apodal grub, which in about twelve days spins a cocoon for itself, and becomes a quiescent pupa, from which the imago emerges in about a fortnight more.

ORDER VIII. DIPTERA.-The anterior pair of wings alone developed; the posterior pair of wings rudimentary, repre

sented by a pair of clubbed filaments, called 'halteres,' or 'balancers.' Mouth suctorial..

The Diptera constitute one of the largest of the orders of the Insecta; the House-flies (Musca), Gnats (Culex), Forest-flies (Hippobosca), and Gad-flies (Tabanida, fig. 66), constituting good examples.

ORDER IX. LEPIDOPTERA.-Mouth suctorial, consisting of a spiral trunk or antlia,' composed of the greatly elongated maxillæ, protected, when not in use, by the cushion-shaped, hairy labial palpi. Labrum and mandibles rudimentary. Wings four in number, flattened, covered with modified hairs or scales. Larvæ vermiform, commonly known as 'caterpillars.'

Fig. 67.-The Silver-striped Hawk-moth (Charocampa celerio).

This well known and most beautiful of all the orders of Insects comprises the Butterflies and the Moths (fig. 67); the former being diurnal in their habits, the latter mostly crepuscular or nocturnal.

The larvae of Lepidoptera (fig. 68), commonly called 'caterpillars,' are vermiform in shape, normally composed of thirteen segments, the anterior portion forming a distinct horny head, with antennæ, jaws, and usually simple eyes. The mouth of

the caterpillar, unlike that of the perfect insect, is formed for mastication. The labium also is provided with a tubular organ -the 'spinneret'-which communicates with two internal glands, the functions of which are to furnish the silk, whereby the animal constructs its ordinary abode, or spins its cocoon, The three segments behind the head correspond with the prothorax, mesothorax, and metathorax of the perfect insect,

and carry three pairs of jointed walking legs. Besides these, a variable number of the segments of the abdomen are provided with soft, fleshy legs, which are called 'pro-legs.'

ORDER X. HYMENOPTERA.-Wings four, membranous, with few nervures; sometimes absent. Mouth always provided with biting jaws, or mandibles; the maxillæ and labium often converted into a suctorial organ. Females having the extremity of the abdomen mostly furnished with an ovipositor (terebra or aculeus).

The Hymenoptera form a very extensive order, comprising the Bees, Wasps, Ants, Ichneumons, Saw-flies (fig. 69), &c. The ovipositor, which is very generally present in the females of this order, is sometimes a boring organ (terebra), or in other cases a 'sting' (aculeus).

Amongst the Hymenoptera we find social communities, in many respects resembling those of the Termites, of which a description has already been given. The societies of Bees and Ants are well known, and merit a short description,

The social Bees, of which the common Honey-bee (Apis mellifica), is so familiar an example, form organised communinities, consisting of three classes of individuals - the males, females, and neuters. As a rule, each community consists of a single female-the 'queen,' and of the neuters, or 'workers.' The impregnation of the female is effected by the production of males, or drones,' during the summer. After impregnation has been effected, the drones, as being then useless, are

destroyed by the workers. The eggs produced by the fecundated queen are mostly intended to give origin to neuters, to which end they are placed in the ordinary cells. The ova, which are to give origin to females-the 'queens' of future

Fig. 69.-Hymenoptera. The Great Saw-fly (Uroceros gigas).

colonies are placed in cells of a peculiar construction, and the larvae are fed by the workers with a special food. The ova, which are to produce males, are likewise placed in cells, which are slightly larger than those allotted to the workers. It is asserted, however, that this is not the sole, or true, cause of the production of the males; but that the ova which are intended to produce drones are not fertilised by the female with the semen which she has stored up in her spermatheca, and are therefore produced by a process of Parthenogenesis. (See Introduction.)

In the Humble Bees (Bombida), and in the Wasps (Vespida), we have societies essentially the same as in the Honeybee.

The Ants (Formica) likewise form communities, consisting of males, females, and neuters. The males and females, as we have seen in the case of the Termites, are winged, and are produced in great numbers at a particular period of the year. They then quit the nest and pair, after which the males die. The females then lose their wings, and fall to the ground, when they become the queens of fresh societies. In some Ants-as in the Termites-the neuters are divided into two classes-the workers and the soldiers-of which the former perform all the