| Abstrakt: |
In 2 stands of red maple in Greene County, Georgia, during 1965–67, most galleries of Corthylus columbianus Hopkins occurred in the lower portion of the bole, the number per foot decreasing rapidly with increasing height, but with no apparent differences in numbers between aspects. Galleries made during the spring and fall were less concentrated near the base of the tree than those made during summer. Most brood beetles apparently established their galleries on the tree in which they were reared. The success of those beetles and their offspring, rather than an influx of beetles from other trees, was responsible for any population upswing that occurred in that tree. The population within the stand during any one attack period was concentrated on a small number of trees which were distinctly aggregated in distribution. The population increased and expanded within the areas of aggregation as the summer progressed. The population and the number of infested trees decreased over winter, and there was an obvious change in the spatial distribution of the population within the stand from one year to the next. Trees of all sizes above 3 inches diameter at breast height and in all crown classes were infested. Dispersal occurred during every attack period. Most newly infested trees were in the vicinity of trees infested during the previous attack period. The data indicated that most or all the trees in the stand were suitable hosts. The aggregated distribution of the population probably resulted from behavior of the adults within a generally susceptible stand. Because most beetles tended to remain on the tree from which they emerged, large numbers built up in certain trees where survival was good, and dispersing beetles tended to fly mainly to nearby trees to establish galleries. Unexplained declines of subpopulations in individual trees, especially over winter, continuous dispersal, and the buildup of subpopulations in new trees resulted in a continuous change in the pattern of population distribution. Over a period of years, most trees in the stands will have been infested one or more times. |
