A native of USA which has become widely established in the UK. It alternates between spruce (Picea) and Douglas fir.  Infestations cause most damage on Douglas fir where foliage can become encrusted in white fluffy wax, sooty moulds and becomes mottled.   On spruce infestations, cause galls which can affect the growth of new shoots.   The adelgid lays eggs in the spring on Douglas fir.   The nymphs soon hatch and feed on the needles producing large amounts of white wax and honeydew.   The adult females are less than 2mm in length and reddish brown to black; both winged and wingless forms occur.   In early summer the winged forms migrate to spruce where they produce a generation that overwinters. In spring the overwintered generation induces elongate galls on spruce.   This generation matures in the summer producing winged females that migrate to Douglas fir and overwinter, laying eggs in the spring.