PERFECT INSECTS WITH THE LARVAL HEAD. 15 



4. Pieris Rapae. 



5. Morpho Eurylochus. 



6. Zygaena exulans. 



7. Sphinx spec. 



8. Bombyx Mori (several times). 



9. Liparis Monacha. 



10. Gastropacha quercifolia. 



11. Zerene adusta. 



12. Botys fuscalis. 

 Coleoptera. — 13. Dytiscus marginalis. 



14. Hydaticus bimarginatus. 



15. Cy bister limbatus. 

 Diptera. — 16. Syrphus spec. 



Only the fact of the presence of the larval head is known for the 

 Nos. 7, 10, 13- 16. More or less sufficient details are known for Nos. 

 1, 3, 8, 12, but the publication by Professor Westwood will give doubt- 

 less a full information about them. The Nos. 4, 11, were only in the 

 chrysalis state, and do not strictly belong here. But just those cases 

 are interesting, as all the others must have passed the chrysalis state in 

 the same manner. 



The Nos. 1, 2, 8, and probably 5, were bred by home raising ; Nos. 3, 

 6, 7, 9, 12, 15, were caught living. 



The interesting fact that the larval head is sometimes retained in the 

 perfect insect is proved by the quoted observations. Probably all cases 

 except Noctua heteroclita belong to the same kind of deformity. The 

 head of the imago is contained in the head of the larva, which the in- 

 sect was not able to cast off in the transformation. It must be admit- 

 ted that circumstantial details are known only for V. Populi, V. Antiopa, 

 M. Eurylochus, Z. exulans. The prothorax of the two last-mentioned 

 species, and even one foreleg in 31. Eurybchus, is still covered by the 

 larval skin. The antenna? are free in B. fuscalis ; the palpi are rejected 

 in V. Antiopa, V. Populi, M. Eurylochus ; in Z. exulans they are free. All 

 specimens were fully developed in size, shape, and colors, except B. 

 Mori. 



Perhaps such deformities are not so rare as the small number of 

 known cases would lead us to believe. Such deformed specimens are 

 more easily caught and destroyed by their natural enemies, or they die 

 sooner for lack of food. Nevertheless, the very large number of Lepi- 

 doptera bred and raised during the past hundred years allows us to con- 

 clude that at least in home raising such deformities occur very rarely. 

 Mr. Trouvelot observed many times T. Polyphemus caterpillars casting oft" 

 the larval head with more or less difficulty, and sometimes not at all. 

 The last case proved to be fatal. As insects of course are developed 

 more easily in liberty than in captivity, the rare occurrence of perfect 



