01Yellowing leaves
| Possible cause | Clemson | Wisconsin |
|---|---|---|
| Armored scale insects | Clemson Cooperative Extension says feeding armored scales remove plant sap, which can turn the foliage yellow. Source: Armored Scale Insects on Ornamental Plants in South Carolina · checked 2026-09-27 | University of Wisconsin–Madison Extension says armored scales inject toxins while feeding on leaf tissue, which kill cells at the feeding site and cause a yellow or brown halo. Source: Scale Insects · checked 2026-09-27 |
| Soft scale insects | No matching line in the Clemson pages we checked. | University of Wisconsin–Madison Extension says a heavy infestation of soft scales can cause yellowed leaves, distorted new growth at the tips, twig dieback, or defoliation. Source: Scale Insects · checked 2026-09-27 |
02Sticky leaves or black film
| Possible cause | Colorado State | Wisconsin |
|---|---|---|
| Soft scale insects | Colorado State University Extension says as they feed, soft scale insects give off a lot of sticky honeydew that can coat the leaves and become a real nuisance. Source: Brown Soft Scale – A Common Insect Pest of Indoor Plants · checked 2026-09-27 Colorado State University Extension says the honeydew left behind by soft scales can lead to sooty mold, a black fungal growth that grows wherever the honeydew lands. Source: Brown Soft Scale – A Common Insect Pest of Indoor Plants · checked 2026-09-27 | University of Wisconsin–Madison Extension says large amounts of honeydew from soft scales can make the plant and everything below it sticky, drawing ants, bees, wasps, and flies. Source: Scale Insects · checked 2026-09-27 |
03Insects you can see
| Possible cause | Clemson | Colorado State | Wisconsin |
|---|---|---|---|
| Armored scale insects | Clemson Cooperative Extension says adult armored scale insects are the most noticeable stage on the plant, and they may be white, gray, or brown. Source: Armored Scale Insects on Ornamental Plants in South Carolina · checked 2026-09-27 Clemson Cooperative Extension says armored scale insects are covered by a hard, waxy shell that protects their body. Source: Armored Scale Insects on Ornamental Plants in South Carolina · checked 2026-09-27 Clemson Cooperative Extension says armored scales don't make honeydew the way soft scales do, and the hard covering over the adult often shows concentric rings or overlapping layers. Source: Armored Scale Insects on Ornamental Plants in South Carolina · checked 2026-09-27 Clemson Cooperative Extension says armored scale crawlers are tiny and look like little specks of dust moving around. Source: Armored Scale Insects on Ornamental Plants in South Carolina · checked 2026-09-27 | No matching line in the Colorado State pages we checked. | University of Wisconsin–Madison Extension says armored scales get their name from the hard, waxy covering over their body. Source: Scale Insects · checked 2026-09-27 |
| Oystershell scale | No matching line in the Clemson pages we checked. | Colorado State University Extension says mature oystershell scales are about 1/8 inch long, brown or gray, and shaped like an oyster's shell. Source: Oystershell Scale · checked 2026-09-27 Colorado State University Extension says newly hatched oystershell scale crawlers are pale yellow, active insects that move around on the bark. Source: Oystershell Scale · checked 2026-09-27 | No matching line in the Wisconsin pages we checked. |
| Soft scale insects | No matching line in the Clemson pages we checked. | Colorado State University Extension says soft scale crawlers usually settle down on stems, though they can also colonize leaf surfaces. Source: Brown Soft Scale – A Common Insect Pest of Indoor Plants · checked 2026-09-27 | University of Wisconsin–Madison Extension says soft scale insects are round to oval and dome shaped, roughly 1/8 to 1/4 inch long when full grown. Source: Scale Insects · checked 2026-09-27 |
04Wilting or dying back
| Possible cause | Clemson | Colorado State |
|---|---|---|
| Armored scale insects | Clemson Cooperative Extension says when the infestation gets severe, armored scales can weaken the plant badly enough to kill a tree or shrub. Source: Armored Scale Insects on Ornamental Plants in South Carolina · checked 2026-09-27 | No matching line in the Colorado State pages we checked. |
| Soft scale insects | No matching line in the Clemson pages we checked. | Colorado State University Extension says a heavy soft scale infestation can make leaves drop early and cause branches to die back. Source: Brown Soft Scale – A Common Insect Pest of Indoor Plants · checked 2026-09-27 |
05Stems and canes
| Possible cause | Clemson | Colorado State |
|---|---|---|
| Armored scale insects | Clemson Cooperative Extension says feeding armored scales remove plant sap, which can cause branches to die back. Source: Armored Scale Insects on Ornamental Plants in South Carolina · checked 2026-09-27 | No matching line in the Colorado State pages we checked. |
| Oystershell scale | No matching line in the Clemson pages we checked. | Colorado State University Extension says when populations are high, oystershell scale feeding can cause limb dieback, and during heavy outbreaks the plant can die. Source: Oystershell Scale · checked 2026-09-27 Colorado State University Extension says areas of bark that oystershell scale damaged before often crack later on. Source: Oystershell Scale · checked 2026-09-27 |
What to do about it. This site only covers how to recognize a problem. For what to do next, open the Extension page linked in the row: their advice is written for their region and is kept up to date by them.
Pages compared on this chart
- Armored Scale Insects on Ornamental Plants in South Carolina, Clemson Cooperative Extension (checked 2026-09-27)
- Oystershell Scale, Colorado State University Extension (checked 2026-09-27)
- Brown Soft Scale – A Common Insect Pest of Indoor Plants, Colorado State University Extension (checked 2026-09-27)
- Scale Insects, University of Wisconsin–Madison Extension (checked 2026-09-27)