45 



* 



Hylesinus do. Hylesinus Fraxini and Hylesiniis orenatas readily burrow into 

 sound trees to hibernate, but as a rule, leave them in spring for timber more 

 suitable for oviposition ; but it has been noted, especially in some pine feeding 

 species, that, when a quantity of felled timber has been left near some isolated 

 trees, so that a large number of beetles enter the latter for hibernation, they 

 are very apt to destroy these in the spring by ovipositing in them. So that 

 in these cases, we might paradoxically say that the beetle itself was the disease 

 that induced its own attack. Were healthy growing trees at all suited to 

 Scolytus Destructor, it is so abundant and so prolific, that in a few years there 

 would not be an elm tree left in the country, yet in this district I have 

 searched in vain for one so attacked. 



Healthy living trees are supposed to resent and repel the attacks of the 

 Hylesinidse by ijouiing out sap into their burrows, and in the case of Scolytus 

 Fruni I have observed burrows of less than an inch long, some of them with a 

 few eggs already laid, which had been abandoned uncompleted by the beetles, 

 and which contained 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 beside some dying bark which had doubtless attracted the 

 beetlei. 



Scolytus multistriatus (Marsh) also lives in elm, and of the remaining 

 species is perhaps the most nearly allied to Scolytus Destructor, from which it 

 differs by being much smaller in size ; the strioe of its elyti-a are very close and 

 consist of uniform rows of puncta, wliile in Destructor the rows are not so 

 close together, jand the alternate rows of puncta are very slightly marked, the 

 others being proportionately deep. Scolytus multistriatus also posesses a blunt 

 spine or tubercle on the centre of the second abdminal segment beneath and 

 directed backwards. It is usually to be found in the same logs as Destructor, 

 aad also in smaller ones down to four inches in diameter. It is much more 

 scarce than Scolytus Destructor, one burrow of Scolytus multistriatus being found 

 for fifty of Scolytus Destructor. The burrows, similar to those of Scolytus 

 Destructor, start from the bottom of a crevice in the bark. They take a longer 

 diagonal course on entering the bark before assuming the typical longitudinal 

 direction, and though usually do not always lie close to the wood. Though 

 much smaller in diameter than those of Scolytus Destructor, they are nearly as 

 long, and I have seen one four inches in length. The number of eggs laid in a 

 burrow is about a hundred. They are deposited behind a continuous layer 

 of frass, which does not encroach on either the floor or roof. The period of 

 oviposition is about a week later than that of Scolytus Destructor. I have several 

 times found a male and a female beetle in the bui-row when it was less than 

 half an inch long, and before any eggs had been laid, but never after that period. 

 The larvffi form their hibemacula in the thickness of the bark, hardly ever in 

 the wood. Scolytus multistriat'us is a much less hardy insect than Scolytus 

 Destructor, and of all the species of Scolytus I had in captivity last winter multi- 

 striatus is the only species of which I failed to rear even a single specimen. 



