Three coleopterous predators associated with the Douglas-fir
beetle (Dendroctonus pseudotsugae Hopkins in a second growth
forest of Douglas-fir (Pseudotsugae menziesii (Mirb. ) Franco)
in western Oregon are Enoclerus sphegeus Fabriciup, E, lecontei
Wolcott, and Thanasirnus undatulus Say. A study was undertaken
with the following objectives: (1) to determine the diurnal...
Behavioral responses exhibited by the Douglas-fir beetle,
Dendroctonus pseudotsugae Hopkins, to various attractant sources
were investigated under both laboratory and field conditions. Tests
were designed to observe olfactory responses. Results were correlated
and compared with collections from sampling nets and with
emergence patterns. Field data were collected during the flight...
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 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,...
Three sympatric species of Ips, colonizing Sitka spruce, were
investigated with regard to their infestation habits, stridulating
apparatus and acoustic signals. The above phenomena are evaluated
qualitatively and/or quantitatively and the acoustic signal differences
are proposed as a possible factor for maintaining species isolation,
although function is not shown.
Field...
Both Leperisinus oregonus and L. californicus are bark beetle
species which emerge from Fraxinus latifolia brood logs as sexually
immature adults and disperse to living ash. Occasional field observations suggest that, for overwintering and maturation feeding, L.
oregonus enter trunks and branches, whereas L.; californicus enter twig
crotches, buds and...
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 balsam woolly aphid (Adelges piceae (Ratz)), an
European pest of conifers, was first discovered in the
Pacific Northwest shortly after 1930. Control measures
of a chemical, silvicultural, or biological nature have
been proposed. However, present control methods are either
too costly or do not result in satisfactory control of...