This family contains about twenty species, several of which rank among the commonest as well as the most beautiful of the _Geometrae_. Their wings are more or less angulated; and the antennae are generally pectinated in the males. The larvae are generally humped and twig-like; and, as in the last species, the semblance is increased by the position they assume when at rest. The number of limbs varies from ten to fourteen, but where the claspers exceed two pairs, the additional two or four, as the case may be, are seldom used in walking. _The Brimstone Moth_ (_Rumia luteolata_) As soon as the warm evenings of May set in, this lively and bright little moth may be seen flitting about among our hedges at sunset; and it continues with us throughout the whole of the summer, but is particularly plentiful during the month of June. The moth itself need not be described, since it is shown on Plate XII (fig. 3); but the caterpillar (fig. 25) must receive a passing notice. It varies considerably in colour, being either green, brown, or marbled with a mixture of shades of both these colours. It has a hump on the back of the seventh segment, and two more on the ninth, and possesses four pairs of claspers. It feeds on whitethorn (_Crataegus oxyacantha_), blackthorn (_Prunus spinosa_), and the apple (_Pyrus Malus_), and may be found on these trees throughout the summer. Some believe that there are three successive broods of this insect each year, but it is doubtful whether this is invariably the rule, since both the moth and its larva are to be found without intermission throughout the season. _The Light Emerald_ (_Metrocampa margaritaria_) All the wings of this moth are very pale green, and crossed with a white band which is bordered with a darker green on the inner side. The fore wings have an additional transverse line just halfway between the former and the base, but this one is not so distinct. It flies in July, and is very widely distributed, and in some parts is very abundant. [Illustration: FIG. 177.--THE LIGHT EMERALD.] The caterpillar feeds in September, and again in May, after hybernation, on several of our forest trees, including the oak (_Quercus Robur_), elm (_Ulmus campestris_), birch (_Betula alba_), and beech (_Fagus sylvatica_). It is of a dingy olive colour, with a dark dorsal line, on each side of which is a row of white spots; and it has three pairs of claspers. _The Scalloped Oak_ (_Crocallis elinguaria_) This species is common and widely distributed, and may be seen flying at dusk towards the end of July and throughout August. It is represented in fig. 4 of Plate XII. The antennae of the male are strongly pectinated; those of the female are simple.