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AbstractRegression models of the form lnY= b0+ b1ln(X?c) + b2Xare presented that describe the within-tree distribution of the pupae of Thanasimus dubius(F.), a clerid predator of the southern pine beetle, Dendroctonus frontalisZimm. More T. dubiuspupae/100 cm2of bark area were found in loblolly pine, Pinus taedaL., than in shortleaf pine, P. echinataMiller, and the number increased with increasing tree diameter class. Peak densities were found at a height of 1?4 m.

AbstractAll four major southern pines can be killed by the southern pine beetle, but loblolly and shortleaf are much more susceptible than longleaf and slash. Oleoresin from more than 50 trees of each species was tested for composition and amount of monoterpenes and resin acids, viscosity, flow (rate, duration, and amount), and rate of crystallization. Discriminant function analyses were used to classify the loblolly and shortleaf trees as to probable resistance. The best classification used physical properties (total flow, flow rate, viscosity, time to crystallization). Supposedly resistant and susceptible trees were subjected to controlled attack, and the chemical and physical properties of four loblolly pines that survived natural attack were measured. Resistance is strongly related to the physical properties of the oleoresin, and can be predicted by these properties. Loblolly and shortleaf trees with “average” properties usually succumb to 100 or more attacks per sq. m of bark surface. Several trees classified as resistant survived a much higher rate of attack.

AbstractA population of the Douglas-fir cone moth, Barbara colfaxiana(Kft.), was studied on the Buckhead Seed Production Area, Lowell Ranger District, Willamette National Forest, Oregon, during 1971. Factors contributing to the mortality of B. colfaxianaare presented in a partial life table and discussed. The egg – instar I was identified as the critical age interval and resinosis the critical factor.

During 1971 a study was conducted to determine the amount of the various Douglasfir cone structures (bracts, scales, and seeds) consumed by the Douglas-fir cone moth, Barbara colfaxiana(Kft.), in the Buckhead Seed Production Area, Willamette National Forest, Oregon. It was not the intent of this study to develop a complete energy budget for B. colfaxiana, but rather to determine the number of calories consumed, on the average, by an individual during the larval stage. The behavior of the various larval instars has been discussed by Radcliffe (1952), Keen (1958), Hedlin (1960), and Nebeker (1977). The calorie was selected as the unit of measure due to its usefulness in modeling energy transfer from one component to another in the forest ecosystem.