128 PROCEEDINGS OF THE 



M. AuDOUiN related the chief results obtained in some 

 researches which he had made for several years relative to the 

 Scolyti, which do so much mischief in our forests, woods, and 

 public walks. M. Audouin said it afforded him pleasure to 

 announce that MM. Wesmael and Spence, with whom he had 

 much communication concerning these insects, and in company 

 with whom he had examined their ravages, particularly at 

 Brussels, in the spring of 1836, wholly coincided with the 

 view which he took of the principal facts connected with their 

 history. He considered the injury to be caused by the perfect 

 insect as well as by the larva. It was an error to suppose that 

 the perfect Scolyti took no nourishment, and employed them- 

 selves solely in propagating their kind ; they were at this 

 period of their existence peculiarly voracious, and attacked by 

 swarms the trunks of trees, in order to extract from them a 

 nutritious juice : they perforate the exterior bark with their 

 mandibles, and, having entered, form for themselves little 

 galleries of various depths, which enter the external layer of 

 the wood of the trees : now this external layer contains a great 

 quantity of viscous sap, or cambium; the Scolyti soon, however, 

 quit these galleries, and leave a round hole where they make 

 their exit. Hence results much evil to the trees ; partly from 

 the loss of sap from the holes, especially in the spring, w^hen it 

 is flowing freely ; and partly because the water, either from 

 rain or melted snow, is admitted, which, once introduced, finds 

 its way under the bark, and produces a disorganization of the 

 tissue to the extent of several inches. Thus it is easy with a 

 little skill to distinguish at once those trees which are sufferinsf 

 from this cause; they may be recognised by black spots in 

 the bark, — not very apparent, it is true, but, when the bark is 

 removed, very obviously depicted on the wood in oval patches 

 as black as ink, and often covered with a liquid of the same' 

 colour. Now it is curious to observe, that these diseased 

 trees, thus rendered sickly, as M. Audouin has assured him- 

 self, by the attacks of the perfect Scolyti, are the very trees 

 which the following year will be selected by the female Scolyti 

 to deposit therein innumerable eggs, whence issue hosts of 

 larvae, which, burrowing in every direction, consign the tree to 

 inevitable death. Nevertheless, it not unfrequently happens, 

 that those trees which have been simply perforated by the 

 perfect Scolyti for nutriment, and which have not been sought 



