44 



on encroaching it. Its construction occupies about three weeks. The eggs are 

 laid along either side close to the bark, the cavities in which they lie being 

 somewhat irregular, not nicely fitting the egg as with Hi/lcsinus. The eggs 

 in a bun-ow number about 100, but I have met with more than 160 in one. 

 They are covered by a rather thick continuous layer of frass which also lines 

 the floor of the burrow, and extends partially on to the roof. The young 

 larvw starting at right angles to the parent gallery, which is parallel with the 

 axis of the tree, form a very reg\ilar 'typograph,' at least in those somewhat 

 rare instances in which contiguous broods do not interfere with each other. 

 Most of the larvai are full-fed in August, and I dare say that, in favourable 

 seasons, there are sometimes two broods in a year. A certain iiroportion assume 

 the pupa state at the end of the larval burrows, become perfect and emerge 

 during the latter part of August, but what becomes of the beetles that thus 

 emerge I do not know. I find no trace either of their ovipositing during 

 the autumn, or of their hybernating, for though Scohjtus Destructor begins 

 its bun-ows earlier than the other Scolyti, it is several weeks later than the 

 Hylesini and other bark-beetles that pass the winter in the perfect state. The 

 greater number of the larvae when full fed burrow about half an inch into the 

 wood, where they form a little longitudinal chamber, the entrance of which in 

 tightly filled with frass, and in this they pass the winter in the larva state, 

 completing their transformations in this cavity in the spring, and emerging 

 about the end of May. In trees with tolerably thick bark, they sometimes 

 form these hibernacula in the latter. 



The object, though not the cause, of this difference in instinct between 

 the beetles emerging in autumn and those remaining as larvte until the spring 

 is obvious. The bark, especially when riddled by Scolytus, soon becomes loose 

 from the action of the weather dui-ing the winter, and when it falls off birds 

 and numerous other enemies quickly remove all exposed larvaj, but those 

 buried in the wood are quite safe ; the little circles of frass marking their 

 openings, when the wood has lost the slight staining it receives from the 

 decomposing bark, are hardly visible ; the little patches of white wood frass in 

 the removed bark are, however, very conspicuous. 



Scohjtus Destructor has a reputation, undoubtedly founded on fact, for 

 attacking and destroying living elm trees. I do not remember having seen a 

 felled ehn trunk that it had not attacked, frequently whilst it was still trying 

 to throw out shoots, yet I have never seen a trace of it in healthy growing 

 trees. One point that is to be observed is that all, or nearly all, recorded 

 instances, and they are by no means few, of its attacking living trees, have 

 oocurred near towns, and (in England) especially near London. 



From this cu-cumstance, it appears extremely probable that the trees in 

 question, though apparently thriving, were really more or less sickly. The trees 

 have also been observed in some instances to have been injured in the first place 

 by the beetles boring into the bark for food, these being probably the autumnal 

 specimens in search of hibernacula, just as I have observed the species of 



