Scolytus. | RHYNCHOPHORA. 405 
broods do not interfere with each other. Most of the larve are full fed 
towards the latter part of July, and I daresay that, in favourable seasons, 
there are sometimes two broods ina 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 Scolytz, 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 larve when full fed burrow about half-an-inch 
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 larve 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 larve; 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, being hardly visible, though the little 
patches of white wood frass in the removed bark are very conspicuous. 
**T 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 Hylesinide 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 must 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 which had doubt- 
less attracted the beetles.” 
Dr. Chapman has observed the habits of all the British species, with 
the exception of S. Ratzeburgit (which has only occurred at Rannoch), 
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 noise 
* M. Bedel (1. c. p. 385) makes the following remark :—‘‘ A part des Scolytus, ils 
ont habituellement deux ¢énérations par an.” 
