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,...
Black bears (Ursus americanus) in western Oregon and Washington peel bark from conifers in early spring to forage on the sugar-rich phloem and cambial tissues. This provides important energy at a time when similarly attractive forage is scarce. Bears often damage Douglas-fir (Pseudotsuga menziesii) trees in stands that are intensively...
Sclereids are sclerenchyma cells having thick lignified
secondary walls. Douglas-fir sclereids, also called bast fibers,
are long (1 mm in length), sharply pointed, spindle-shaped fibers
of a red-brown color. Sclereids from Douglas-fir bark and nine
other western coniferous species were examined for their morphology.
The external surface characteristics of sclereids...