Fig. 72 represents, from Charles de Geer's Memoir, the pupa of the Reduvius personatus covered with dust, and resembling a spider; [Fig. 73] the same insect cleaned, freed from the cloak of dust which served to disguise it.
Fig. 74.—Hydrometra stagnorum.
The Hydrometræ (from ὑδωρ, water, and μετρειν, to measure) have linear bodies. The head, which forms nearly the third of the entire length, is furnished with two long antennæ, and armed with a thin, hair-like beak. The legs are long, and of equal length. The reader may have often seen the Hydrometra stagnorum walking by jerks on the surface of the water ([Fig. 74]). The body and legs are of a ferruginous colour, the hemelytra a dull brown, and the wings hyaline, or glassy, and slightly blackish. Geoffroy says that it resembles a long needle, and calls it the Needle Bug.
The Hydrocorisæ, or Water Bugs, have the antennæ shorter than the head, or scarcely attaining to its length, and inserted and hidden under the eyes, which are in general of remarkable size. All these Hemiptera are aquatic and carnivorous. We will mention the two principal types, the Nepæ, or Water Scorpions, and the Notonectæ, or Boatmen.
Fig. 75.—Nepa cinerea.
The Nepa cinerea ([Fig. 75]), which Geoffroy calls the Oval-bodied Water Scorpion, and which he also designates by the name of the Water Spider, is very common in the stagnant waters of ponds and ditches. Its body, oval, very flat, of an ashy colour, with red on the abdomen, is four-fifths of an inch long. The hemelytra are horizontal, coriaceous, and of a dirty grey colour. Its front legs, with short haunches, and very broad thighs, are terminated by strong pincers, which give to the insect a strong resemblance to the scorpion. It is by folding back the leg and the tarsus under the thigh, that the animal holds its prey, and sucks it with its rostrum or beak.