ON THE r,AKVA OF 'I'll E GLOW WORM. 77 



(J. On the Methods of Feeding and the Moijth-parts o£ the 

 Larva of the Grlow-worm {Lampyris noetiluca). By 

 Kathleen Haddon, Zoological Laboratory, Cam- 

 bridge *. 



[Received Juno 26, 1914: Read February 23, 1915.] 

 (Pinto Lt) 



In mux. Page 



El hology 77 



Structure 7i< 



In many insects of widely separated groups digestion takes 

 place partly outside the body, digestive fluids being exuded from 

 the mouth upon or into the food, which is then sucked up iii a 

 liquid form. The mouth-parts are in some cases specially formed 

 in connection with this habit, while in other cases there appear to 

 be no peculiar modifications. 



One type of modification seen in a few forms is that in which 

 the mandibles are either grooved or pierced l>y a fine tube, and 

 in which the groove or tube is the channel of egress for the 

 digestive fluid, although there seems to he no clear evidence of 

 this, except perhaps in the case of the Dytiscid larva 1 : such modi- 

 fication is apparently found only in insects which feed chiefly 

 or entirely upon the juices of their prey. 



The glow-worm larva is one of those forms in which the man- 

 dibles are pierced by a fine tube, and as it feeds upon snails and 

 sings and leaves no residue, excepting the slime of its prey, 

 Mr. F. Balfour-Browne suggested that J should study the mouth- 

 parts to ascertain whether the food was eaten or sucked up. 



A certain amount of spirit-material was available for dissection, 

 but we were fortunate; in obtaining a, number of nearly full-grown 

 living specimens at Wicken Fen in May. 



Specimens required for section-cutting were first softened for 

 about forty-eight hours in Perenyi's fluid, dehydrated, cleared in 

 cedar-wood oil, and embedded in paraffin in the usual way. The: 

 sections were cut 8 /x thick and stained on the slide, first with 

 eosin in ninety per cent, alcohol, then with picro-nigrosin in 

 water. 



External Features and Habits. 



The larva3 were kept in an inverted bell-jar nearly filled with 

 moist earth, and supplied with some moss. They were caught on 

 May 14th, and for about a week were fairly active arid ready to 

 eat ; but subsequently they became torpid, refused their food, and 

 finally began to pupate— by June 1st all had pupated. 



* Communicated by Frank Balfour-Bkowne, M.A. (Oxon. <•( Cantab.), 

 F.R.S.E., F.Z.S. 

 t For explanation of the Plate see i>. 82. 



