The eggs hatch and the young insects winter there. In the spring, they feed on the needles, mature and lay eggs. The eggs hatch and the adults which eventually develop may remain on the fir to fly back to spruce to lay eggs for a new generation. The presence of Douglas fir is not necessary, however, as the adelgids can maintain themselves on spruce alone. No effective parasites exist.
Some trees are resistant to adelgids.
Do not fertilize infested trees. Douglas fir is an alternative host. Do not plant blue spruce and Douglas fir together. No effective parasites are available. Do not plant Douglas fir with blue spruce.