Some insects injurious to forests . l theirbodies are fully hardened orchitinized. When nearly readyto emerge, the adults bore theirway almost to the surface ofthe bark (fig. 12, a), but pausebefore emerging, appearing torest in the burrow, they havejust made. They do not, how-ever, hollow out the space im-mediately adjoining the pupacase, as is the habit of anotherspecies of this genus. Whenquite ready to emerge, the bee-tles continue their burrows outthrough the remaining portionof the bark. The individualsof a brood do not appear toemerge simultaneously, butthey come forth at irregular in-t
Some insects injurious to forests . l theirbodies are fully hardened orchitinized. When nearly readyto emerge, the adults bore theirway almost to the surface ofthe bark (fig. 12, a), but pausebefore emerging, appearing torest in the burrow, they havejust made. They do not, how-ever, hollow out the space im-mediately adjoining the pupacase, as is the habit of anotherspecies of this genus. Whenquite ready to emerge, the bee-tles continue their burrows outthrough the remaining portionof the bark. The individualsof a brood do not appear toemerge simultaneously, butthey come forth at irregular in-tervals until all are out, leavingthe bark thickly punctured withsmall, round, clean-cut holes,as shown in figure 12. After leaving the tree or t in -in which they went throughtheir transformations the bee-tles fly away to find trees inwhich to deposit eggs. Theymay select trees close at handor may fly quite a longdistance before making a selectionalso enter the living bark of recently felled trees. Larg<61830°—Hull. 58—10 o. 11.—The western pine-destroying oarkbeetleDendroctontu brevicomis). Pitch tubes on bark ofi iriginal. | They willnumbers i f 26 SOME INSECTS INJURIOUS TO FORESTS. the beetles usually settle upon a few trees close together and crawlabout upon the bark from near the base to about two-thirds of thedistance to the trees top, seeking suitable places for entrance. Crev-ices in the bark are favorite places with them for this purpose. Thefemale appears to bore the entrance hole in the bark, and may ormay not be closely followed by her mate. In some cases where gal-bries had just been started, females were found alone, that is, onefemale to a single gallery. In others, the female was followed by themale. As the first incision is made into the living inner bark, the treebegins exuding pitch to cover the wound made by the intrudingbeetle. This pitch or resin collects at the mouth of the entrance hole in the form usually known asa pitch tube (figs. 11 and 12,
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectinsectp, bookyear1910
