Spruce Bud Scale

Scientific Name: Physokermes piceae
Scientific Type: Scale Insects

Spruce bud scale (Physokermes piceae) is a small insect pest that feeds on the needles of spruce trees, including blue spruce, Engelmann spruce, and white spruce. The adult female scale insect is covered in a white, cottony wax that protects her as she feeds on the sap of the tree's needles. This feeding causes yellowing and needle drop, which can result in significant defoliation and stress on the tree. The insect also produces a sticky honeydew that can attract sooty mold and other insects, causing additional damage to the tree.

The lifecycle of the spruce bud scale includes a crawler stage, in which the newly hatched nymphs move about in search of suitable feeding sites. They then settle down and begin feeding, molting into their adult form and reproducing. The females lay eggs under their wax coverings, which hatch into crawlers that move on to new needles to feed.

Spruce bud scale can be difficult to control because of the protective wax coverings that the females produce. Pruning affected branches and removing fallen needles can help to reduce populations, and insecticidal treatments can be effective when applied during the crawler stage. Cultural practices such as proper watering, fertilization, and avoiding injury to the tree can also help the tree to withstand scale insect damage.