.] RHYNCIIOPHORA. 405 



broods do not interfere with each other. Most of the larvae are full fed 

 towards the latter part of July, aud I daresay that, in favourable seasons, 

 there are sometimes two broods in a year.* A certain proportion assume 

 the pupal state at the end of the larval burrows, become perfect and 

 emerge during August ; but what becomes of these beetles I do not 

 know. I find no trace either of their ovipositing during the autumn, or 

 of their hybernating ; for, though S. destructor begins its burrows earlier 

 than the other Scolyti, it is several weeks later than the Sylesini and 

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

 greater number of the larvse when full fed burrow about half-an-iuch 

 into the wood, where they form a little longitudinal chamber, the 

 entrance of which is tightly filled with frass, and in this they pass the 

 winter in the larval 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 their hybernacula in the 

 latter. 



" The object of this difference in instinct between the beetles emerg- 

 ing in autumn, and those remaining as larvae until spring, is obvious. The 

 bark, especially when riddled by Scolytus, soon becomes loose from 

 the action of the weather during the winter, and, when it falls off, birds 

 and numerous enemies quickly remove all exposed larvae ; but those 

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

 their openings, when the wood h-is lost the slight staining it receives 

 from the decomposing bark, being hardly visible, though the little 

 patches of white wood frass in the removed bark are very conspicuous. 



" I do not remember seeing a felled elm trunk that S. destructor had 

 not attacked, frequently whilst still trying to throw out shoots yet I 

 have never seen a trace of it in healthy growing trees ; these are supposed 

 to resent and repel the attacks of the Hylesinidce by pouring out sap 

 into their burrows ; and, in the case of S. pruni, I have observed burrows 

 less than an inch long, some of which, containing a few eggs already laid, 

 had been abandoned uncompleted by the beetles, apparently on account 

 of the presence of a fluid which nmst have been sap, as no rain had 

 fallen to account for it ; these burrows had been formed in bark that 

 was still nearly healthy, though near some dying bark wliich had doubt- 

 less attracted the beetles." 



Dr. Chapman has observed the habits of all the British species, with 

 the exception of S. Ratzeburgii (which has only occurred at Eannoch), 

 in the district around Abergavenny, and in the paper just quoted from 

 gives an account of each ; next to S. destructor he has found S. intricatus 

 the commonest species ; in conclusion he remarks that in all the species 

 the female dies in the burrow after oviposition is completed : S. destruc- 

 tor, intricatus, and pruni are able to make an audible stridulating n< ise 



* M. Bedel (1. c. p. 385) makes the follow ing remark : " A part des Scolytut, ils 

 ont habituellement deux generations par au." 



