Half hours with insects . Gyrinus and larva. 150 HALF HOURS WITH INSECTS. [Packard. Fig. 114. dalns (Fig. 114), which transforms into the large net-veinedinsect (Fig. 115) so formidable in appearance, and yet soharmless. A singular chapter in biology would be the lifeof this insect. The gigantic carnivorous larva, with its large head and enor-mous jaws, is providedwith eight pairs of long,rather stiff, respiratoryfilaments. Dr. Ilagenhas called attention tothe spiracles of this crea-ture, which are not usu-ally present with trachealgills, and to the reasonfor their existence. Itseems that like
Half hours with insects . Gyrinus and larva. 150 HALF HOURS WITH INSECTS. [Packard. Fig. 114. dalns (Fig. 114), which transforms into the large net-veinedinsect (Fig. 115) so formidable in appearance, and yet soharmless. A singular chapter in biology would be the lifeof this insect. The gigantic carnivorous larva, with its large head and enor-mous jaws, is providedwith eight pairs of long,rather stiff, respiratoryfilaments. Dr. Ilagenhas called attention tothe spiracles of this crea-ture, which are not usu-ally present with trachealgills, and to the reasonfor their existence. Itseems that like the Euro-pean Sialis (Fig. 116,larva and pupa) it livessome weeks out of waterbefore its transformationinto the pupa, whichrests in an earthen co-coon in the banks ofstreams above eggs (Fig. 114, a)are very large, and aredeposited In a squarishmass on the steins ofwater plants. There is no more beau-. Corydalus larva and egg tifnl object for low powers of the microscope than the larvalMay fly (Fig. 117). The body is so transparent that themovements of the heart, the play of its valves, the circula-tion of the blood, the distribution of the tracheae, the diges-tive canal and its movements, as well as the action of the 22 Packard.] IXSECTS OF THE POND AND STREAM. 151 muscles controllingthe jaws and otherparts of the mouth,can all be watchedwith ease. The tra-cheal gills, like pad-dles, either round orlong and leaf-like,are arranged in pairsalong the hinder re-gion of the body,and the tracheae inthem can be readilyseen. These beauti-ful respiratory leavesare also paddles, andby their aid as well asby the undulations ofthe body the 3oungMay fly moves rap-idly and gracefullythrough the lives two years,while tbe winged fly(Fig. 118) but a day,rarely over twenty-four hours. Thewinged fly throwsoff the pupa skin inan instant. Whileholding a pupa inmy hands the im-ago slipped out s
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectinsects, bookyear1881
