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TEXT-BOOK OF ENTOMOLOGY 



a 



nal segments, and we find in accordance with this circumstance that the pupal 

 envelope is still very thin and delicate, and has little or no hardening or rough- 

 ness by which to obtain a leverage against the walls of the channel of escape." 

 (Trans. Ent. Soc. London, 1896, pp. 570, 571.) 



Some sort of a beak or hard process, more or less developed, 

 according to Chapman, adapted for breaking open the cocoon exists 

 in nearly all the Lepidoptera with incomplete pupae (pii[> j hi<-nm- 

 pletce), except the limacodid and nepticulid section. " In all these 

 instances the pupa emerges from the cocoon precisely as in the 

 Micropteryges, that is, the moth it really is that emerges, but does 

 so encased in the pupal skin. To achieve this object, it seems to 

 have been found most efficient to have three, four, or five abdominal 

 segments capable of movement, but to have the ter- 

 minal sections (segments) soldered together." 



This cocoon-breaker, as we may call it, is especially 

 developed in Litliocolletis hamadryadella. As de- 

 scribed by Comstock, it forms a toothed crest on the 

 forehead which enables it to pierce or saw through 

 the cocoon. 



"Each pupa first sawed through the cocoon near its junc- 

 ture with the leaf and worked its way through the gap, by 

 means of the minute backward-directed spines upon its back, 

 until it reached the upper cuticle of the leaf. Through this 

 cuticle it sawed in the same way that it did through the 

 cocoon. The hole was in each case just large enough to per- 

 mit the chrysalis to work its way out, holding it firmly when 

 partly emerged. When half-way out it stopped, and presently 

 the skin split across the back of the neck and down in front 

 along the antennal sheaths, and allowed the moth to 



emerge." l 



We have observed and figured the cocoon-breaker 

 in Bucculatrix, Talseporia (Fig. 590, ), Thyridop- 

 teryx, and (Eceticus, and rough knobs or slight pro- 

 O f Tatep 5 oria: <Tco* j^^tion answering the purpose in Hepialidse, Megalo- 

 pyge, Zeuzera, and in Datana. 2 See also the spine 

 on the head of Sesia ti^nlifonnis (Fig. 578). - 



The imago of the attacine moths cuts or saws 

 through its cocoon by means of a pair of large, stout, black spines 

 (sectores coconis), one on each side of the thorax at the base of the 

 fore wings (Fig. 591), and provided with five or six teeth on the cut- 

 ting edge (C, D). 



of four pairs 

 abdominal Irirs, 



1 the creiu:i>t(T. 



1 Rep. Ent. U. S. Dept. Agr., 1879, pp. 228, 229, PI. IV, Fig. 4. 



2 Monograph of bombyciue moths, Pt. I, 1897. Figs. 2i, 28, 29, 33, 34, 40, 77. 



