. Economic entomology for the farmer and fruit-grower . Dragon-fly and its development.—Lar\a and pupa feeding at 1 and 3; 2, nymph ready to change; 4, a pupa skin from which 5, the adult, has emerged. The early stages are passed under water, and the larvae are ugly creatures, somewhat resembling the adults, but without wings. They move sluggishly among the aquatic vegetation, or on the mud of the bottom, strongly resembling the latter in color. They do not swim readily, but some are able to propel themselves by drawing into the posterior part of the digestive tract a quantity of water and the
. Economic entomology for the farmer and fruit-grower . Dragon-fly and its development.—Lar\a and pupa feeding at 1 and 3; 2, nymph ready to change; 4, a pupa skin from which 5, the adult, has emerged. The early stages are passed under water, and the larvae are ugly creatures, somewhat resembling the adults, but without wings. They move sluggishly among the aquatic vegetation, or on the mud of the bottom, strongly resembling the latter in color. They do not swim readily, but some are able to propel themselves by drawing into the posterior part of the digestive tract a quantity of water and then expelling it forcibly. This process really answers a double purpose, for this same tract is supplied with numerous fine tracheal tubes through which oxygen is drawn from the water : two functions, respiration and locomo- tion, being thus curiously combined. Respiration is also carried on by means of leaf-like anal appendages, in which trachea ramify- in all directions, forming gill-like structures. As the larvae grow, wing-pads appear, and when these are fully developed the pupal stage has been reached ; the insects continuing active, however,
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectbenefic, bookyear1906
