194 Younrj Larvae o/ Lyctus bruniieiis Steph. 



The wood tissues, which constitute the food of the larva, are, after 

 passing the crushing apparatus referred to, further broken up in the 

 proventricuhis. This consists of longitudinal rows of short chitinised 

 setae. In the full-grown larva there are eight rows (Text-fig. 2, 5, 6), 

 four superior and four inferior. 



The proventriculus, oesophagus, pharynx, and the trophi are cast at 

 each ecdysis. 



It was observed that the larva's method of boring is partly assisted 

 b}'^ the following, (a) Its habit of packing the frass behind it into a com- 

 pact mass by means of continual pressure of the curved apex of the 

 abdomen against the frass; in this, it is aided by the wood tissue con- 

 tained in its convoluted proctodeum. (6) By slightly revolving as it 

 bores, thus enabling it to bite out a bore which is circular in transverse 

 section and in more or less*the one plane, (c) Its possession of a large 

 quantity of body fluid, which flows rapidly under control and functions 

 in a manner somewhat similar to the body fluid of an emerging Cyclo- 

 rhaphous Dipteron. 



The legs were seen to be used to assist it in revolving, and for clearing 

 out particles of wood tissue, or the frass of another bore into which it 

 had struck. The dorso-lateral thoracic region was observed to fit closely 

 to the bore when distended by the body fluid, but the legs were free to 

 move within the cavity formed by the lateral epi-pleural lobes and the 

 sternum. 



Conclusions. 



The rudimentary compound eyes, which are present in all the larval 

 stages of L. brunneus, are most clearly defined in the first and second 

 instars. Their presence being probably due to their existence in the 

 remote free-living ancestral larva. 



The retention and value of them to a wood-boring larva at first 

 appear obscure, but, when it is remembered that the young first instar 

 larva works its way along the vessel towards the point of access of its 

 parent's ovipositor, to consume the residual-yolk-mass, it is coming 

 towards light, and the surface of the wood; the value of its eyes is 

 obvious. The larva is helpless on the surface of the wood. (None were 

 ever able to get back into a vessel after being placed on the surface.) 



In the second instar the value and the use of its eyes are clearly 

 demonstrated by the observations in the foregoing account of the second 

 instar larva's behaviour in the small pieces of wood used iii the breeding 

 experiment. For, when it found itself in a vessel at the side it always 



