following three months ; and twelve months later, as no other adults 

 emerged, the logs were split open to ascertain their contents. 



The whole centre of the log was intersected by tunnels, 

 and eleven burrows contained larva? of HInjsm persuasoria, of 

 whom eight were full fed and three about half grown. Only three 

 larvfe of Sirex remained ; two of these were in burrows not 

 communicating with tunnels; the third was probably similarly 

 placed, but its position is uncertain as it fell out while the wood 

 was being split. It was evident that the lihyssa larv^ had been 

 unable to reach these three in their solitary burrows. 



The larvae of Sirex are white and fleshy furnished with mouth- 

 parts of the usual wood-boring type, and the apex of the abdomen 

 carries a chitinous spiked process for assisting the six prolegs in 

 propelling the larvae along the tunnels. 



The Illujasa larv^ are also white and fleshy but legless, and 

 move by muscular contractions of the folds of skin which form 

 lateral expansions of the abdomen. The mouth-parts are of a 

 degenerate, parasitic type ; the maxillae are fused with the mandibles 

 to form a chitinous hooked proboscis, and the palps are merely 

 represented by unsegmented sense organs. Prior to pupation the 

 proboscis is used for collecting minute chips left by Sirex larvae in 

 their tunnels, and teasing them into a very fine soft material with 

 which to line the burrow. 



The Sirex larva which had been injured when the logs were 

 split, was placed in a box together with three lihyssa larvae : the 

 next morning each had its proboscis plunged into the luckless Sirex. 

 I separated them, placing wads of cotton wool between them and 

 their prey, but the next day they had made their way through the 

 wool to their victim, and little remained of the Sirex larva but an 

 empty skin. 



The logs further contained two adults of Sirex (jinas which had 

 died on the point of emerging. It was not difficult to realise the 

 cause in the first specimen, for the exit was blocked by a hard knot 

 of wood impossible to pass. At first sight it was not obvious what 

 had baulked the second specimen until upon moving it a RIn/.ssa 

 larva was discovered occupying the corpse which had been reduced 

 to a few chitinous rings, the head and wings only entire. 



The l\/ii/ssa and Sirex larvae were replaced in portions of the log 

 and sealed up again, but a most regrettable accident destroyed all 

 this material and put an end to further observations. 



