ENTOMOLOGICAL SOCIETY OF FRANCE. ] 29 



by the females on the following year, not only survive, but 

 recover, at the end of two or three years,- their pristine vigour. 

 Trees also which have been attacked by a few females only, 

 have, in some instances, appeared to revive. It often also 

 happens to the ehici, that trees to which the perfect Scolyti have 

 yet done no injury in seeking for food, are nevertheless 

 attacked by females, and eggs are deposited upon them ; but, 

 when this is the case, it is always observable, that the tree is 

 suffering from some other cause,- — either a canker, or some 

 wound which had facilitated the introduction of rain-water. In 

 other instances the elms had been attacked by the larvae o^Xyleu- 

 tes cossns, of which the number is sometimes very considerable. 

 M. Audouin remarked, that these various causes induced the 

 same result, namely, sickness to the tree, and consequent non- 

 ascension or slow circulation of the sap ; this state of sickness 

 is indispensable to the laying of the eggs of the Scolytus, and 

 it appears of little consequence to the parent how it has been 

 superinduced. This fact has undoubtedly imposed on those 

 persons who have asserted, that none but those trees which 

 were either dead or inevitably dying were ever attacked by 

 the Scohjti. Those who assert this are certainly in error ; 

 for it is without doubt ascertained that, in the greater number 

 of cases, the tree, notwithstanding its diseased state, would 

 have recovered had it not been for the subsequent oviposition 

 by the female Scolyti. With regard to Scolytus pygmwuSf 

 which produces such devastation among the oaks, M. Audouin 

 observed that this insect, besides perforating in the perfect 

 state the bark of the oak-trees, often also attacks, and this 

 with the only aim of obtaining proper food, the young shoots 

 of the year while they are still green, cutting them at their 

 base. Some species of oak are much more liable than others 

 to be attacked in this particular way, and the tree itself suffers 

 much from the continued injury. We may observe in the 

 botanical garden of the Jardin-du-roi, a Portugal oak, {Quercus 

 Lusitanica,) which is regularly stripped of its young shoots 

 to'«vards the middle or end of June. Its trunk and branches 

 are still very healthy ; its bark is very hard and rough ; and it 

 seems that the Scolyti, which are of the species pygmwus, find 

 it difficult to pierce ; hitherto, therefore, they have not depo- 

 sited their eggs in this tree, but have confined themselves to 

 the sap of the young shoots. M. Audouin gave it as his 



NO. II. VOL. V. s 



