Pine needle scale, Chionaspis pinifoliae, is a conspicuous and common armored scale insect on conifers throughout the United States. Pine needle scales appear as oyster shell-shaped white blisters on the needles of conifers, often so numerous they envelop the entire needle. Although they prefer pines they are known pests of spruce, fir, and Douglas fir causing disfiguration and often death of the infested needles and general decline of the whole tree.
Treatment Strategy
Pine needle scale is an armored scale that can have two generations per year. Insecticide applications must be timed to ensure high titer levels are within the tree when nymphs insert their mouthparts into the needles and begin to feed. Apply Transtect to the soil in the spring up to 2-3 weeks prior to crawler emergence. Two foliar spray applications should be timed to target new crawlers from each generation. Transtect soil applications have provided good results on leaf feeding armored scales such as False Oleander Scale, Pine Needle Scale and Elongate Hemlock Scale.
Foliar Spray, Soil Application, or Lower Basal Bark Spray Using Transtect
Trunk Injection Using Transtect Infusible
Foliar Spray Using Proxite + RTSA Horticultural Oil
Foliar Spray Using RTSA Horticultural Oil
Foliar Spray Using Up-Star Gold
Expected Results
Transtect has performed extremely well in trials as a soil application on pine needle scale.
Signs of Damage
- Sickly, yellow appearing needles
- Heavily infested trees can appear silvery from a distance
- Thin or weak appearing canopies as infested needles are shed
- Presence of numerous, oval shaped white insects on needles
Trees At Risk
- Pines, especially Mugo (Pinus mugo) and Scots pine (P. sylvestris)
- Fir (Abies spp.)
- Spruce (Picea spp.)
- Douglas fir (Pseudotsuga menziesii)
Biology
- First generation eggs hatch over 2-3 weeks in mid-spring (283-448 GDD).
- Second generation eggs hatch over 2-3 weeks in mid-summer (1290-1917 GDD).
- Crawlers move to the previous year’s needles to insert their mouthparts through the stoma to feed upon which they begin to form new armor.
- 3-5 weeks later the males emerge as winged adults. Females emerge as wingless adults.
- After mating, the females grow for a couple more weeks and lay 20-60 deep reddish colored eggs under the armor.
- Eggs overwinter under the armor.
- Two generations per year.
References
USDA Forest Service
https://www.fs.usda.gov/Internet/FSE_DOCUMENTS/stelprdb5351723.pdf
Ohio State University
https://bygl.osu.edu/node/1248
Penn State Extension
https://extension.psu.edu/pine-needle-scales
Always refer to product label for rates and approved uses. Some images courtesy of forestryimages.org or Wikimedia Commons. Use of the images does not imply endorsement of treatments.
