THE ENTOMOLOGIST 



Vol. XXXIX.] 



OCTOBEE, 1906 



[No. 521. 



IMPERFECT MOULT IN A LARVA OF AMORPHA 

 (SMERINTHUS) POP U LI. 



By T. A. Chapman, M.D., F.Z.S. &c. 



Mr. South forwards to me a larva, given to him by Mr. 

 Norman Riley, of Amorpha {Sinerinthus) populi in its last instar, 

 the victim of an accident at moulting, viz. the retention of the 

 larval head of the previous skin, the moulting otherwise being 

 successful. This accident is not very rare, and is more or less 

 familiar to those who breed many Lepidoptera. I fancy I have 

 seen it perhaps fifty times. A short memorandum on the con- 

 dition of such a larva may be useful, as I do not for the moment 

 recollect any notice of it in our text-books or magazines. 



At moult the new head is much larger than the old one, and 

 the difficulty of the new head being within the smaller old one 

 is overcome by its leaving the old one and occupying the pro- 

 thoracic segment of the old skin. Room is made for it tliere by 



ENTOM. — OCTOBER, 1906. U 



