File:Economic entomology for the farmer and fruit-grower - and for use as a text-book in agricultural schools and colleges (1906) (14591274290).jpg

Identifier: economicentomo00smit (find matches)
Title: Economic entomology for the farmer and fruit-grower : and for use as a text-book in agricultural schools and colleges
Year: 1906 (1900s)
Authors: Smith, John Bernhard, 1858-1912
Subjects: Insect pests
Publisher: Philadelphia London : J.B. Lippincott company
Contributing Library: University of British Columbia Library
Digitizing Sponsor: University of British Columbia Library

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o be weapons of offence.The legs are stout, clothed with spines and spurs, as well as withlong claws at the tip. The mouth is formed for biting, the man-dibles and maxillae being greatly developed and sharp-toothed,for tearing their prey. They are, as has been indicated, predaceous, and capture theirfood during flight, their powerful wings and legs enabling them toovertake and grasp any creature that comes within the range oftheir huge eyes. Flies and mosquitoes are the usual victims, and THE INSECT WORLD. 6l hence the term mosquito hawk has also been applied tothem. It has been suggested that dragon-flies might be artificially-propagated to lessen the mosquito pest ; but this is not feasible,because they fly only during the day, while the mosquito isdecidedly more a creature of the night. No dragon-fly volun-tarily remains in woods, except along streams and in open glades,yet here mosquitoes lurk by the million. The proposition lookswell at first sight, but is not practical. Fig. 32.
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Dragdii-fly and its development.—I,ar\a and pupa feeding at i and 3; 2, nymph readyto change ; 4, a pupa skin from which 5, the adult, has emerged. The early stages are passed under water, and the larvae areugly creatures, somewhat resembling the adults, but withoutwings. They move sluggishly among the aquatic vegetation, oron the mud of the bottom, strongly resembling the latter incolor. They do not swim readily, but some are able to propelthemselves by drawing into the posterior part of the digestivetract a quantity of water and then expelling it forcibly. Thisprocess really answers a double purpose, for this same tract issupplied with numerous fine tracheal tubes through which oxygenis drawn from the water : two functions, respiration and locomo-tion, being thus curiously combined. Respiration is also carriedon by means of leaf-like anal appendages, in which trachea ramifyin all directions, forming gill-like structures. As the larvae grow,wing-pads appear, and when these are full

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