64 BRITISH LEPIDOPTERA. 



the cocoon precisely as in the Eriocraniids, but not, as a rule, so com- 

 pletely, and to do this the pupa seems to have found 8, 4, or 

 5 abdominal segments capable of movement necessary, but to have 

 kept the terminal segments soldered together. Many different means 

 have been adopted to enable the pupa to free itself from the cocoon, 

 such as specially constructed weak places in the cocoon, a particular 

 arrangement of the silk that allows free egress with but slight internal 

 pressure, a softening fluid applied by the newly-emerging moth, pupal 

 spines of different kinds, and even imaginal spines (Actias), &c. 

 Comstock describes the "cocoon-breaker" in Lithocolletis (liama- 

 dryadella) as a toothed crest on the forehead which enables it to pierce 

 or saw through the cocoon. Of its action in some individuals that he 

 was observing, he writes : " Each pupa first sawed through the cocoon 

 near its juncture 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 permit 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." Packard notes the similar structures in Bucculatrix, 

 Taleporia, Thjridopteryx, and (Eceticus, and states that rough knobs or 

 slight projections answer the purpose in Hepialids, Megalopygids, 

 Zeuzerids, &c. He further calls attention to the spine on the frontal 

 point of Sesia tipidiformis. 



Packard states that " the imagines of the Attacine moths cut or saw 

 through the 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 

 forewings, and provided with five or six teeth on the cutting-edge." 

 He further notes that the "cocoon-cutter" occurs "in all the 

 American genera, in Samia cynthia, and is large and well marked in 

 the European Satumia pavonia-minor and Endromis versicolor. In 

 Platy samia the cocoon-cutters, though well- developed, do not appear to 

 be used at all, and the pupa, like those of the silkworm and other 

 moths protected by a cocoon, moistens the silk threads by a fluid 

 issuing from the mouth, which also moistens the hairs of the head and 

 thorax, together with the antennae. It remains to be seen whether 

 these structures are only occasionally used, and whether the emission 

 of the fluid is not the usual and normal means of egress of the moth 

 from its cocoon." Trouvelot says that this fluid is secreted during the 

 last few days of the pupal state, and is a dissolvent for the gum that so 

 firmly unites the fibres of the cocoon, the liquid being composed in 

 great part of " bombycic acid." One is inclined to enquire for what 

 purpose E. versicolor imago has a cocoon-cutter, seeing that the pupa 

 emerges from the cocoon. 



With regard to the manner in which the silk of the cocoon is 

 moistened from the mouth of the emerging moth by certain Saturniids, 

 &c, in order to enable them to escape from the cocoon, Chapman 

 gives some interesting details (Ent. Mo. May., vii., pp. 81-82), referring 

 more especially to I'latysamia cecropia. One is inclined at first to 

 question the possibility of this happening at all, for it is just these 

 moths that have no proboscis and hardly any oral appendages that 



