Scales in Christmas Trees
go.ncsu.edu/readext?646261
Elongate Hemlock & Other Scales
Scales are some of the hardest to find and most difficult to control of Christmas tree pests. Many scale pests are of regulatory importance and trees and greenery shipped to other states and countries are frequently inspected for scales. Sound cultural practices, careful scouting, and wise pesticide use will go a long way to reducing issues with scale pests.
Online Information – NC State University
CTN 37: Elongate Hemlock Scale & Other Scales – fact sheet with photos and information on life cycles, cultural practices, and control recommendations of several scale pests.
CTN 31: Pine Tortoise Scale – fact sheet with life cycle and control measures
Pine Needle Scale – PDIC fact sheet
Monitor Pine Needle Scale – information on the life cycle of pine needle scale in North Carolina
Focus on Scale Control – including pesticide recommendations
EHS – Facts at a Glance – quick facts about elongate hemlock scale (1-page pdf version with photos)
Cryptomeria – Facts at a Glance – quick facts about Cryptomeria scale (1-page pdf version with photos)
Videos
How to Scout for Elongate Hemlock Scale
Making Wreaths to Avoid Scales (English version)
Making Wreaths to Avoid Scales (Spanish version)
Keeping Trees Scale Free (English version)
Keeping Trees Scale Free (Spanish version)
Long-Term Scale Control Studies – from the 2020 Virtual Christmas Tree Farm Tour
Insecticide Trial for Scale Control – from the 2020 Virtual Christmas Tree Farm Tour
Scouting for Christmas Tree Predators – including biological control organisms for scales
Photo Gallery
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- Close-up of active elongate hemlock scale on Fraser fir
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- Occasionally scales will create yellow patches known as mottling on needles
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- Filaments from male elongate hemlock scale are easily visible as males are developing
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- Elongate hemlock scale crawler settles under the waxy covering of the needle
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- Adult female of elongate hemlock scale
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- This adult female has been flipped over and teased open to show several eggs
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- This adult female has been flipped over to show the shield-like area through which the sscale feeds. Also note the crawler emerging at the far end.
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- Emergent holes from parasitic wasp in elongate hemlock scale female
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- Cryptomeria scale nymphs resemble fried eggs on underside of needle
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- Cryptomeria scales can stack one on top of the other, making control more difficult
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- Cryptomeria scale can often lead to premature needle loss
Other On-Line Resources:
University of Florida IFAS Publication #ENY2040: Elongate Hemlock Scale, and Exotic Scale Pest of Christmas Trees and Other Conifers – elongate hemlock scale risk to Florida conifers
Trees, Forests & People, Vol. 2, December 2020: Evaluating the invasive potential of an exotic scale insect associated with annual Christmas tree harvest and distribution in the southeastern U.S. – final publication from the host study to evaluate the risk of elongate hemlock scale to Florida conifers
USDA Alien Forest Pest Explorer: Elongate Hemlock Scale map
Penn State Extension: Elongate Hemlock Scales – identification and control