Nov., '03] ENTOMOLOGICAL NEWS. 28r 



terminal ones kept at the surface. The tracheal system under- 

 goes no change with larval growth, except the odd develope- 

 ment about the anal spiracles which is shown in the compara- 

 tive diagrams (Figs. 2, 3). 



Is the food derived from the twig or from the resin ? I made 

 note of the following points : i . The mouth-parts are exceed- 

 ingly soft and delicate. 2. The young grow rapidly near the 

 surface of the resin . 3. The twistings of perhaps a dozen spiny- 

 skinned larvse hollow and smooth out a round cavity, the irrita- 

 tion causing a constant supply of fresh resin, so that no lump 

 containing live larvae ever becomes entirely hardened. This 

 soft resin is full of microscopic splinters of wood fibre, which 

 would probably have been consumed had the larvae detached 

 them with their mouths. The digestive tract, so far as I 

 could ascertain, contained none of them. 4. Where the resin 

 supply was abundant, without any activity on the part of the 

 larvae, no cavity was formed and no splinters were present in 

 the resin, although the larvae continued to grow normally. 5. 

 I placed a drop of resin upon which nineteen eggs had been 

 deposited in the laboratory, upon the smoothly cut surface of 

 a sound twig. There was a fair flow of resin, and in two 

 weeks, and even after two weeks, when the larvae were quite 

 large, the only damage to the twig was a small spot just 

 beneath them where the cells appeared dead. There was, how- 

 ever, no roughening or cavity. 



The pupae measure 5 millimeters in length. The head and 

 appendages are covered by a black pupal integument, only the 

 shrunken abdomen retaining its deep orange color. They lie 

 with their heads toward the surface of the lump, inside the 

 innermost end of the detached larval skin, which is not shed, 

 pupation going on within it. The loosened skins are white 

 and papery, and extend to the surface with their inner ends so 

 closely packed that they adhere to each other, and slightly to 

 the twig. Thus the whole eight, or perhaps a dozen, form a 

 core-like mass with irregularly radiating rays, which can be 

 lifted out entire more easily than separately. 



When ready to emerge, the insect pushes itself outward by 

 a backward and forward movement of the thorax and abdo- 



