Tribe II.—Subulicornia.
The second tribe of the Pseudo-neuroptera contains a group of insects which are so similar to one another in form that they are all included in one family.
Family 3, Ephemeridæ.—The Ephemeridæ, or Day Flies, as they are popularly called, are delicate, elongated, soft-bodied creatures, with a moderately small head. The antennæ, which spring from the forehead below the ocelli, are short and awl-shaped. These insects, which seem to be found mostly in temperate climates, are remarkable for the great delicacy of their structure, and for the extreme shortness of their lives in the perfect state, which seems in general scarcely to exceed a day.
Nearly fifty species of Ephemeridæ occur in this country. The best known is Ephemera vulgata, of which the sub-imago is called the "green drake," and the imago the "grey drake" by anglers. The two-winged Clöen diptera, which, however, is a much smaller species than the foregoing, is also very abundant.
Fig. 56.—Calopteryx Virgo (Female).
Tribe III.—Plecoptera.
The Plecoptera contain only one family.
Family 4, Perlidæ.—The Perlidæ, or Stone Flies, are chiefly inhabitants of the temperate regions; they are of small size, and not very numerous in species, about thirty being indigenous to the British Isles.
The larvæ, which are aquatic in their habits, closely resemble the perfect insect in form. Their food consists of other insects and they prey especially upon the larvæ of the Day Flies.