. Introduction à la botanique. La botanique. FOEESTRY ; BOIS 123. 6. Bois-boriiig-feuille et manger des insectes devrait être tué, si les frais de la procédure n'est pas trop grand. Il est suggéré, par exemple, que les grands dommages causés par le dendroctone du pin- détruire, wliich tue les arbres matures par l'exploitation minière l'écorce du tronc, peut être beaucoup moindre. Cela peut être accomphshed par couper et d'enlever la plupart des arbres infestés ou par rif- dhng arbres au début de juin, à l'exposer aux attaques de l'insecte, puis l'abattage et l'autre de les peler ou immersion dans l'eau, de détruire les insectes avant que le nouveau cro

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. Introduction to botany. Botany. TIMBER; FOEESTRY 123. 6. Wood-boriiig and leaf-eating insects should be killed, if the expense of the process is not too great. It is suggested, for example, that the great damage caused by the spruce- destroying beetle, wliich kills mature trees by mining the bark of the trunk, may be much lessened. This can be accomphshed by cutting and removing most of the infested trees or by gir- dhng trees early in June, to expose them to the attacks of the beetles, then felling and either peeling them or immersing them in water, to destroy the insects before the new crop of beetles emerges from under the bark the following June.^ One of the most effectual means of destroATUg some injurious insects con- sists in uitroducing into the region where they abound parasitic or other insects which will kill great numbers of the objectionable species. Plant lice, for in- stance, are thus killed by ladybugs. ^'^igorous attempts are now being made to exterminate the g}'psy moth in Xew England by means of parasites and by carnivorous insects (fig. 100) which at- tack and kill the moth at some stage of its existence. The caterpillars of tins moth are extremely destructive to many kinds of trees, which they strip of their leaves ia a short time. IMore than a million dollars has probably been expended in ^Massachusetts alone in trying to get rid of this pest. The moth was introduced into America in 1869, by a scientist who Hved at iledford, near Boston, in the course of some most unfortunate experiments on silk-producing insects.^ Pig. 100. A carnivorous beetle (Cahsojna syco- p?ianta) which destroys the caterpillars of the gypsy moth These beetles have been imported from Euroim, and successful colonies of them established in XeTv England. After United States Department of Agriculture 1 See "Insect Enemies of the Spruce in the Northeast, " BuUelin 2S. New Series, Division of Entomology, U.S. Dept. Agr., 1901. 2 "The Gypsy iloth in America, &quot

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