The study (1) describes the life cycle of P. nebulosus,
(2) examines stimuli that may cause the beetles to locate brood
material, and (3) establishes the relationship between moisture
stress in Douglas-fir and colonization by P. nebuZosus.and other
meristem insects.
(1) Development of P. nebulosus goes through the egg stage,...
Factors considered were phloem moisture, sour-phloem (which
may be furthered by the presence of ample phloem moisture), oleoresin of the host, and the presence of unmated female beetles in
suitable host material.
Levels of phloem moisture present in variously prepared logs
in the field ranged from about 100 to upwards...
The purpose of this study was to study in some detail
host factors which influence the population dynamics of
bark beetle. The dissertation objectives were to ascertain
the applicability of utilizing osmotic pressure
values and relative turgidity values of phloem tissue as
indicators which reflect upon the physiological profile
of...
The study was undertaken to determine the seasonal and diurnal
flight patterns of scolytid beetles inhabiting a second growth
forest of Douglas-fir (Pseudotsuga menziesii (Mirb.)Franco) in western
Oregon. Air temperatures, relative humidity, light intensity, and wind
velocities were recorded for evaluation of their influence on flight activity.
The insects were...
The objectives undertaken in this study were:
1) to develop means of identifying the immature stages of
the known insect predators and parasites of the Douglas-fir beetle; 2) to investigate the possible distribution,
spatially and/or temporal, of the known insect predators
and parasites in standing trees infested by the Douglas-fir...
The sinuous flight behavior of male Douglas-fir tussock
moths, Orgyia pseudotsugata, (McD.), is characterized by
positive anemotaxis and positive chemoklinotaxis and varies
depending on distance from the pheromone source, population
density, and time of day. Visual cues play a minor role
in close-range orientation to a pheromone source, but
males...