492 FAMILY SCOLYTIDAE 



the felled poles, the larvae had hatched out, become full-fed, pupated, and 

 emerged as beetles. All this was plainly decipherable ; but the examination 

 showed that, whilst the work was evidently so recent as to have been done 

 during the year, it was not fresh enough to have been that of the beetles then 

 swarming in the forest. The exit-holes made by the beetles had had time to 

 dry and shrivel round their edges, and the boring was no longer fresh and 

 clean. It is probable that the poles were attacked in April, soon after being 

 felled, and eggs laid in them. The beetles maturing from these eggs issued 

 some time in June, and at once laid eggs in other trees, the poles in which 

 they themselves had matured having become too dry to afford food of the 

 nature required by the larvae. These would be the eggs of the second 

 generation, and beetles from them would appear in August. This theory 

 was entirely supported by finding beetles and larvae in some newly felled 

 poles on the 6th of that month. The insects had settled upon these 

 poles, which were unbarked, in a swarm, and the bark was pitted with their 

 entrance-holes. Beneath they were to be found in various stages of egg- 

 laying. In some cases but one beetle was present, having just bored down 

 to the cambium layer. In others two were to be found in the chamber, 

 whilst in others again the egg-gallery had been commenced, or was 

 partially complete, the eggs first laid (at the bottom end) having already 

 hatched out. These beetles were evidently not those of the genera- 

 tion which had attacked the April poles, since they had obviously but just 

 left the tree in which they had matured, and we have seen that the exit- 

 holes in the April poles had dried-up edges. I therefore conclude that they 

 belonged to an intermediate generation, probably the second of the year, and 

 were laying the eggs of a third. 



The beetles evidently leave the trees together when mature, and fly off 

 in a swarm in search of trees in a condition suitable for egg-laying. 



As far as observations have been carried, it would appear that this 



beetle is capable of making itself felt as a serious pest in 



Relations to the the forest. It has evidently the power of swarming 



Forest. j,-, considerable numbers, and requires fresh bark in 



which to lay its eggs. At present it has only been found 



in newly felled poles, but it is more than probable that it would attack 



young growing saplings, especially sickly ones, were the former not available. 



Poles inspected, which had been attacked by the insect, and which the 



beetles on maturing had left, were found to have their bast layer completely 



riddled by the pest, whilst the bark externally showed, in addition to the 



entrance-holes, numerous elliptical rings of exit-holes placed close to one 



another, as shown in fig. 323. An examination showed me that this insect 



appears to be fairly free from parasites, as a close inspection failed to disclose 



any larval remains in the larval galleries and pupating-chambers. In the 



cases where larvae have been attacked it is generally possible to find at 



least the skin of the head and perhaps a portion of the thorax and abdomen 



present in the pupal chamber or larval galler}-. Further, the holes in the 



