RAVAGES BY INSECTS. 159 



state of health ; it is in regard to some, if not all, of the latter olass 

 alone, that there is any question. 



" Authors," says M. Perris,* " seem generally disposed to admit 

 that insects, the larvae of which are developed in the trees, while 

 they are yet growing, are the primary cause of the death of these. 

 There has thus been attributed to the Pissodes notatus the loss of an 

 immense quantity of pines, which covered, in 1835, 190 hectares of 

 the forest of Eouvray. 



" The Marquis of Chambray, in his beautiful work on the resinous 

 trees, speaks of an insect of the genus Bostriche, which, when it in- 

 creases in great quantities, can destroy entire forests of the maritime 

 pine. We read in the Histoire de I' administration en France, par 

 A.nthelme Costaz, t. I., p. 248, that in the seventeenth and eighteenth 

 centuries the pine forests of Germany were so ravaged by the scolyte 

 that the Hanoverian province of the Hartz feared a total loss of fuel, 

 and was delivered from the fear mainly by the effects of several cold 

 and wet winters, which caused the insects to perish in great numbers. 



" As for myself," says he, " I cannot admit that these insects are 

 the primary cause of the death of the trees which they attack, and in 

 fifteen years, during which I have, without intermission, studied their 

 habits in one of the best wooded countries in France, I have observed 

 a sufficiency of facts to justify me in expressing my opinion, which is, 

 that insects in general (not including those which attach themselves 

 solely to the foliage, as miners, etc.) do not attack those trees which 

 are in good health, but they only address themselves to those whose 

 health and functions have suffered, from some cause or other ;'' and 

 he subsequently expresses it as his painful conviction, that lignivorous 

 insects are only to be dreaded by sickly trees. They are like some 

 mosses and lichens which only attach themselves to enfeebled trees, 

 while healthy, well-growing trees, preserve a smooth bark, and 

 repulse these vegetable parasites. 



" In the department of the Landes," says he, " where we reckon the 

 pine trees by millions, I have never witnessed, and tradition has not 

 preserved the recollection of a single case of these forest razzias which 

 have afflicted other countries. Now the pine is exposed to a crowd of 

 enemies, and the number of individuals of the most injurious of these 

 is incalculable, and yet it is but seldom the case that one of those trees 

 perishes, and I have still to find one which has been actually killed 



* Annal Soo. Ent. France, 2mo Series, X, 513. 



