4. Female insects naked, or covered with secretion either waxy, cottony, or felted; abdomen in all stages ending in prominent processes; legs either lost or retained at full growth. Coccidinæ. _Life-history._ The life-history of the insects in the above groups is as follows:-- All of them pass through four stages of existence: 1, the egg; 2, the young larva; 3, the second stage of life, or "pupa;" 4, the adult, or full-grown insect. 1. _The egg._ This is, in all cases, of regularly-oval form, the colour varying from white to yellow or red (see Plate i., Fig. 1). It may be produced in great numbers, and in some cases several times in a year. As a general rule, the female ejects the eggs from her body; but there are some species, notably in the group _Lecanidinæ_, where the eggs are hatched within the body, the insect being thus, in a manner, viviparous. 2. _The young larva_ (Plate i., Fig. 2). This is of precisely the same form both for the male and the female--or, rather, perhaps it should be said that no definite character has yet been discovered to show which are male and which are female larvæ. Neglecting slight variations of form, the larva is very minute--seldom more than about 1/30 in. long, often as small as 1/100 in.--oval, flattish, possessing a rostrum and accompanying bristles (setæ), six legs, and two antennæ: and in all species it is fairly active, travelling as soon as hatched over the plant in search of food. 3. _The second stage._ Here the first distinction is noticeable between the male and the female in most cases; but this distinction usually depends not so much upon the form of the insect as upon the character of the covering it makes for itself. Confining ourselves at present to the female, there are differences now noticeable between the groups. In the _Diaspidinæ_ the insect begins by slipping out of the skin of the larva; but it does not cast it aside altogether: it makes use of the old skin as part of its covering. Adding to it a small portion of fibrous secretion--produced by organs called "spinnerets," which will be noticed presently--it attaches itself to the plant by its rostrum and setæ, and lies, inert and stationary, under a little shield composed half of its old skin and half of secretion. As it also, in entering this stage, loses its legs altogether, it must remain in the position it has chosen for the rest of its life. In the _Lecanidinæ_ and in the _Coccidinæ_ the skin of the larva is thrown away altogether, and the female in her second stage takes up a new position, in which she may be either naked or covered with a thin coat of secretion, active or stationary, retaining her legs in most cases, or losing them in some instances. In all the groups there is almost always some approach to the form of the full-grown insect noticeable in this second stage.