364 Insects most itijun'oiis to Cultivators : — 



her numerous progeny very soon completing the destruction of 

 the tree. Hence it happens that, although the bark of an ehn tree 

 may be the abode of numerous perfect scolyti, the death of the 

 tree is not necessarily consequent thereon, unless it is subse- 

 quently selected by the female for the reception of her eggs ; 

 and, indeed, trees so inhabited but which have not been thus 

 selected, have been observed to recover their health in the space 

 of two or three years. 



When M. V. j!\udouin, on the 4th January, 1837, communi- 

 cated his observations upon this subject to the Entomological 

 Society of France, the Baron Feisthamel, whose brother is the 

 superintendant of the Royal Park of Vincennes, opposed these 

 views of M. Audouin, contending that the extraordinary mor- 

 tality which had occurred in the two preceding years in the 

 trees of that park was attributable to the extreme dryness of 1835 ; 

 the scolytus being but a secondary cause : he, in fact, believed 

 that the insects attacked only trees in an unhealthy state, and 

 that dryness of the weather was the chief cause of the propaga- 

 tion of such immense numbers. The mortaHty of the trees was 

 stated to have occurred only in those districts which were desti- 

 tute of vegetable soil, and where the roots of the trees, being 

 necessarily near the surface, were unable to reach a depth of 

 constant moisture Of 50,000 trees which had been felled, a very 

 small portion was found upon good soil. The Baron Feisthamel, 

 at the meeting of the Entomological Society of France, in July 

 last, read a short memoir upon the same subject, in which he still 

 maintained the same views. On referring, however, to the pro- 

 ceedings of the same Society for February, 1836, we find a 

 statement of facts made by the samfe member, which, in my 

 opinion, clearly proves the scolyti to have been the chief authors 

 of the mischief. 



In the spring of 1835, a great number of the young leaves of 

 the trees were observed to be shed, having been cut off at the 

 petiole; and, in the course of the summer, the bark of the diseased 

 trees was found to be bored with numerous minute holes; when, 

 on pulling off the bark in the vicinity of these holes, there was 

 found in a burrow, which was to be traced from the hole in a 

 transverse direction (the burrows of the young grubs being 

 always longitudinal), a small dead scolytus. In the summer 

 months, the larvae were less abundant ; but, in September, their 

 numbers were increased to such an extent, and the bark so com- 

 pletely filled with them, that, in a piece of bark 8 in. by 6 in. in 

 size, not fewer than 135 larvae were to be counted. The cold 

 of the following winter had no other effect upon them than to 

 render them torpid. 



It is to be noticed, in considering these statements, that no 

 observation is made as to the unhealthy state of the trees in the 



