We now pass on to the second section of Lepidoptera. [Illustration: Fig. 173.--Meadow brown (_Satyrus_ [_Hipparchia_] _janira_).] It contains _those whose flight in the majority of species is nocturnal or by twilight, but by day in some species. The antennæ are more or less swollen out in the middle or before their extremities, and, independently of that, sometimes prismatic, sometimes cylindrical, sometimes pectinated or indented. The body--which was small in comparison to the wings, and which was remarkably thin between the thorax and the abdomen in the first section of Lepidoptera--is in this section very much larger in proportion to the wings, and is not drawn tightly in between the thorax and the abdomen. The wings are horizontal or slightly inclined when the insect is at rest; the upper then cover the lower, which are generally comparatively short and kept back by a bridle on the first, in the case of the males only._ [Illustration: Fig. 174.--Sesia apiformis.] [Illustration: Fig. 175.--Six-spot Burnet Moth (_Zygæna filipendulæ_).] We will take the genus _Sesia_ as the representative of the _Sesiidæ_. These singular insects have membranous wings, and resemble various species of Hymenoptera. The largest species is the _Sesia apiformis_ (Fig. 174), that is, bee-like, which is found in this country, resting on the trunks of willows and poplar-trees, from the end of May till the middle of July. It resembles a hornet, and is of the same size and has the same colours; only they are not quite so bright. When this moth is just hatched its wings are ferruginous; but its scales, light and caducous, fall as soon as the insect begins to fly. The caterpillar, which lives in the trunks or roots of willows and poplar-trees, is of a yellowish colour. The pupa is long, of a brownish colour, enclosed in a cocoon composed of agglutinated saw-dust, the product of the caterpillar's erosions. [Illustration: Fig. 176.--Cocoon of the Zygæna filipendulæ.] In the middle of summer the meadows are frequented by moths, with brilliant black and velvety wings, marked with red, which fly heavily, and only for a short time together. They remain motionless during the great heat of the day. These are the _Zygænæ_, or Burnets, of the family of the _Zygænidæ_. The Ram Sphinx of Geoffroy, or the Six-spot Burnet Moth (_Zygæna filipendulæ_, Fig. 175), is common from the end of June till the beginning of August. Its legs, antennæ, head, and body are black and rather hairy; its upper wings are of a brilliant bluish green, with six spots of a beautiful red on each, bordered by a little green. The caterpillar is yellow, spotted with black; its cocoon is boat-shaped, with longitudinal furrows, and is straw colour (Fig. 176).