Entomology : with special reference to its biological and economic aspects . ighly developed inLepidoptera and the most elaborate cocoons are those of Satur-niidse. The cocoon of Samia cecropia is a tough, water-proofstructure and is double (Fig. 215), there being two air spacesaround the pupa; thus the pupa is protected against moistureand sudden changes of temperature and from most birds aswell, though the downy woodpecker not infre(juently ])unc-tures the cocoon. ,S. cecropia binds its cocoon lirmly to a Cocoon of Cliiysopa,after emergence ofimago. Slightly en-larged. I/O ENTOMOLOGY twig; T
Entomology : with special reference to its biological and economic aspects . ighly developed inLepidoptera and the most elaborate cocoons are those of Satur-niidse. The cocoon of Samia cecropia is a tough, water-proofstructure and is double (Fig. 215), there being two air spacesaround the pupa; thus the pupa is protected against moistureand sudden changes of temperature and from most birds aswell, though the downy woodpecker not infre(juently ])unc-tures the cocoon. ,S. cecropia binds its cocoon lirmly to a Cocoon of Cliiysopa,after emergence ofimago. Slightly en-larged. I/O ENTOMOLOGY twig; Tropcca luna and Tdca polyphcmus spin among leaves,and their cocoons (with some exceptions) fall to the ground;Callosaniia pronictlica, whose cocoon is covered with a curvedleaf, fastens the leaf to the twig with a wrapping of silk, sothat the leaf with its hurden hangs to the twig throughout thewinter. The leaves surrounding cocoons mav render theminconspicuous or may serve merely as a foundation for thecocoon, \\diile silk and often a water-proof gum or cement Fig. 21 Cocoon of Sainia cecropia, cut open to show the two silken layers and the enclosed pupa. Natural size. form the basis of a cocoon, much foreign material, such as bitsof soil or wood, is often mixed in; the cocoons of many com-mon ArctiidcC, as Diacrisia Iirgiiiica and Isia Isabel la, consistprincipally of hairs, stripped from the body of the larva. Butterflies have discarded the cocoon, the last traces ofwhich occur in Hesperiidse, which draw together a few leaveswith a scanty supply of silk to make a flimsy substitute for acocoon. Papilionid and pierid pupa? are supported by a silkengirdle (Fig. 27), and nymphalid chrysalides hang freely sus-pended by the tail (Fig. 212). Cocoon-Spinning.—The caterpillar of Tcica polyphcmus feels with its head in all directions, to discover any leavesto which to attach the flbres that are to give form to the co-coon. If it finds the place suitable, it begins to wind a laye
Size: 2221px × 1125px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, booksubjectentomology, bookyear1
