=Coleoptera: the beetles.=--TECHNICAL NOTE.--Obtain specimens of various beetles, among them some water-beetles and June-beetles with their young stages, if possible; if not, then the young stages and adults of any beetle common in the neighborhood of the school. Of the swimming and diving water-beetles there are three families, viz., the Gyrinidæ or whirligig beetles, with four eyes (each compound eye divided in two), the Hydrophilidæ, or water-scavengers with two eyes and antennæ with the terminal segments thicker than the others, and the Dytiscidæ or predaceous water-beetles with two eyes and slender thread-like antennæ. Try to find Dytiscidæ, large, oval, shining black beetles; the larvæ are called water-tigers and are long, slim, active creatures with six legs and slender curving jaws (see fig. 76). The June-beetles are the heavy brown buzzing "June-bugs" and their larvæ are the common "white grubs" found underground in lawns and pastures. Have live water-tigers and predaceous water-beetles in the aquarium. Note their feeding and breathing. Compare the external structure of the beetles with that of the other insects, noting especially the biting mouth-parts, and their thickened horny fore wings serving as covers for the folded membranous hind wings. [Illustration: FIG. 70.--The forest tent-caterpillar moth, _Clisiocampa disstria_, in its various stages; _m_, male moth; _f_, female moth; _p_, pupa; _e_, eggs (in a ring) recently laid; _g_, eggs hatched; _c_, larva or caterpillar. Moths and caterpillar are natural size, eggs and pupa slightly enlarged. (Photograph by M. V. Slingerland.)] [Illustration: FIG. 71.--A trio of apple tent-caterpillars, _Clisiocampa americana_, natural size. These caterpillars make the large unsightly webs or "tents" in apple-trees, a colony of the caterpillars living in each tent. (Photograph from life by M. V. Slingerland.)] [Illustration: FIG. 72.--A family of forest tent-caterpillars (_Clisiocampa disstria_), resting during the day on the bark, about one-third natural size. (Photograph from life by M. V. Slingerland.)]