Some insects injurious to forests . ectly healthyand not in or around the old scars. In-deed, the habit of the larvae appears torender this quite necessary for their moreor less isolated work. It was particularlynoted that the remaining unaffected barkof the trees which had suffered most fromprevious generations of the insect wasthickly infested with hibernating larvae,while that of near-by large trees which hadescaped previous injury contained veryfew, thus indicating that from some causethere are individual trees which are moreor less immune. This fact, which has beenso often observed, sugge
Some insects injurious to forests . ectly healthyand not in or around the old scars. In-deed, the habit of the larvae appears torender this quite necessary for their moreor less isolated work. It was particularlynoted that the remaining unaffected barkof the trees which had suffered most fromprevious generations of the insect wasthickly infested with hibernating larvae,while that of near-by large trees which hadescaped previous injury contained veryfew, thus indicating that from some causethere are individual trees which are moreor less immune. This fact, which has beenso often observed, suggests the importance of experiments in the prop-agation of immune stock by means of seed or root cuttings fromimmune trees growing among badly infested ones. The hibernating habits of the larvae also suggest a simple methodof destroying them, namety, the cutting and barking of the treesduring the period between the first of November and the first of simple removal of the bark, without burning, is sufficient to killthe OOT£/fB/IAK Fig. 5.—The locust borer (Cyllenerobiniae): Hibernation or larvalcells in outer portion of livinginner bark. About natural size(original). THE LOCUST BOKKK. 11 Oy/c/acf It should be remembered that all the hole- found in a tree and allother damage by the borer are not the work of one generation, but usually that of repeated annual attack during the life of the tree;also, that a burrow in the sapwood of a young tree remains the sameburrow in the heartwood of the old tree, without change, except inthe healing- of the original entrance; therefore the number of Itorersand the amount of damage each year is notso great as it might appear, and, while eachfemale is doubtless capable of depositingmore than a hundred eggs,-- it would ap-pear from the writers observations thatonly a small percentage of the larva1 hatch-ing from them survive the bark-infestingstage or complete their development to theadult stage. This suggests that any methodof m
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectinsectp, bookyear1910
