Do not plant blue spruce and Douglas fir together. No effective parasites are available. Do not plant Douglas fir with blue spruce. On small trees, pruning and destroying galls before insects emerge may be helpful. There are no effective parasites or predators.
Some trees are resistant to adelgids.
Glaucous evergreens such as blue spruce may temporarily lose their blue color if horticultural oil is applied and the natural bloom may not return for 1-2 years. Douglas fir shows a tendency toward sensitivity to dormant sprays of horticultural oil. It is strongly recommended that home gardeners refer to these publications for more information on pest control. Contact our office for information on ordering a copy. This publication contains pesticide recommendations.