Pine Needle Scale
Scientific Name: Chionaspis pinifoliae
Pine Needle Scale is a hard or armored scale. They are aphid-like insects that produce a hard waxy shell to protect themselves from predators and environmental conditions. Pine needle scale females resemble legless bumps and damage plants with their sucking mouthparts. The smaller male scales have wings and while in the nymph stage also feed on plants. Female scale continue to feed as they produce over a hundred eggs under their shell . The mature female dies, but the eggs survive the winter under the protection of the shell. In the spring and summer of the following year, the eggs hatch into an immature stage called the “crawler” stage. The crawlers, also called nymphs move out from under the shell and find a new location on which to feed. As they settle they begin to produce their hard shell. Pine needle scales feed primarily on the needles of trees. Unlike soft scales and aphids, which feed from the circulatory system of the tree, armored scales feed on the contents of individual cells. Since they destroy cells, they can cause significant dieback of infected stem tissues and in severe infestations, even the death of trees.
Attacks: Colorado blue spruce, Norway, white spruce, Arborvitae, cedars, Douglas fir, hemlock, junipers, larch, and pine
What you will see:
- Thin sparse needles
- White spots on needles
- White, waxy scale covering
- Small infestations can increase within one growing season
- Extensive needle and branch mortality
Life cycle:
- Red-colored eggs over-winter under the scale covering
- Eggs hatch in late May / early June
- The new crawlers emerge over a two week period
- After mating, the males die and females produce eggs
- Two generations per year
- Second emergence of crawlers appears in late July
- Each female produces over 100 eggs
Management of Pine Needle Scale
Cultural practices:
- Maintain tree health
- Reduce stress in environment by reducing or enhancing watering
- Root enhancement system
- Mulch
Chemical control:
- Systemic soil injection
- Horticultural oils in Fall (use on non-blue cultivars only)
- Crawler sprays
Please consult with your Arborist for best treatment options.
Management of armored scales is more difficult than for soft scales and aphids, since their hard shells protect them from most topical insecticides. Fortunately there are insecticides that can be used to systemically treat hard scales. The scales ingest this insecticide while feeding and one treatment will usually provide enough control to reduce most hard scale populations to non-damaging levels.
In severe scale infestations this soil injection treatment should be combined with a growing season spray for the susceptible crawler stage of the scale species followed by a late season horticultural oil spray to suffocate any remaining overwintering scales. Horticultural oils should not be applied when the temperature will be above 80° F or on plants with a blue coloration. Oils will remove the blue color from blue spruce, fir and other plants where the wax is blue.
An integrated approach
When caring for urban trees it is important to make a complete evaluation of all environmental conditions to accurately diagnose all stress factors and prescribe care based on specific circumstances. This prescriptive care will help your tree meet its full potential.
