The Mode of Progression of the Larva of Coleophora 

 nigricella. {Plate I.) 



By E. J. BuNNETT, M.A., F.E.S. Read Febnianj ISth, 1919. 



Last sainmer I placed a number of hawthorn leaves, on which 

 were larvae of this little moth, in a glass-topped box. Sometime 

 afterwards several of the larvfe, no doubt finding their pabulum 

 becoming dry and unpalatable, had journeyed to the lid of the box 

 and could be seen moving along the glass. 



Since the greater part of the body of the larva was enclosed in 

 its " case," and only the anterior portion could possibly come into 

 contact with the surface of the glass, it was obvious that motion 

 could not be assisted by means of pro-legs or suction. 



In order to discover how they managed to retain a hold or walk 

 about, hanging downwards from the smooth surface of the glass 

 while supporting not only their own weight but also that of their 

 cases, one of them was transferred to a glass slip. This was turned 

 upside down and placed under a low power objective. 



The mode of procedui-e was then apparent. 



In order to move along, the larva protrudes its he.ad and the true 

 legs from its case, making with its mouth a little " blob" or mound 

 of a viscid secretion, from which it carries a thread as far as it can 

 reach with its mouth, where another mound is deposited. 



The thread connecting two mounds is free, saggmg a little, and 

 does not adhere to the surface. 



The moment this cable is laid it is strong enough to support the 

 ■entire weight, both of the little creature and of its domicile. 



The first two pairs of legs are used for clasping this silken rope 

 and the larva progresses at a surprising rate, always supported by 

 either the first or second pair of legs ; for while the second pair 

 continues to hold on to one loop of the cable, the front pair de- 

 taches itself from it and clasps the next and newest loop, and so on. 



The larva does not hang suspended by a thread from the mouth 

 while in the act of walking in this inverted position, though no 

 doubt it could and would do so in case it were accidentally com- 

 pelled to lose its hold of the clasping legs. 



A remarkable feature of this curious mode of locomotion is that, 

 as in the case of spiders, there is, apparently, more than one kmd 

 of secretion capable of being simultaneously emitted, for the little 

 mounds are viscid enough to adhere to the surface with sufficient 

 tenacity to support the successive sections, while on the contrary. 



