Fig. 41.—A Stone-fly (Pteronarcys regalis).
(From Comstock.)
Suborder [Plecoptera] (πλεκτος, plaited; πτερον, wing). Closely allied to the latter suborder is the suborder Plecoptera, which includes the single family Perlidæ or Stone-flies. The larvæ and pupæ of these insects are aquatic, being often found under stones in water, whence the name. The adults are long, flattened insects, with long antennæ. The wings are ample and are somewhat folded or plaited, from which character the suborder takes its name.
Suborder [Odonata] (οϑους, tooth). This includes the Dragon-flies or Libellulidæ, the most common and the best known of the Neuroptera. The larva and the active pupa or nymph are aquatic and are predaceous, as is also the adult. A common species is represented at see [Fig. 33]
Fig. 42.—A May-fly
(Potamanthus marginatus).
(From Packard.)
The Suborder [Ephemeroptera] (εϕημερον, a day-fly; πτερον, wing) comprises the May-flies, or Ephemeridæ (see [Fig. 42]). These insects are very fragile and are often attracted in enormous numbers to electric lights. They have large front wings, while the hind wings are small, rudimentary, or wanting. They are furnished with two or three very long, jointed, threadlike caudal appendages. The larval and nymphal stages are passed in the water and aquatic vegetation furnishes the food, although some species may be predaceous. The adults have very rudimentary mouths and eat nothing; their term of life is also very limited, not exceeding 2–4 days.
Fig. 43.—(Lepisma 4-seriata).
(After Packard.)
Suborder [Thysanura] θυσανος, tassel; ουρα, tail). This suborder comprises minute, degraded insects commonly known as Spring-tails, Bristle-tails, Fish-moths, Snow-fleas, etc. They occur in damp situations and also infest books, wall-paper, etc., eating the starch paste in the book-bindings, or beneath the wall paper. They comprise very primitive forms and are interesting because they are supposed to represent the original stock from which the higher orders of insects have sprung. They are wingless, usually with simple eyes, and clothed with scales, and undergo no metamorphosis. Some of them, as the Fish-moth (Lepisma sp.), run very rapidly and are furnished at the end of the body with a number of long bristles. In other forms these anal bristles or stylets are united at the base and bent under the body and become a powerful jumping organ, giving them the very appropriate name of Spring-tails.