The Pest-Health Relationship
Before getting into specific pests: the single most important principle in tree pest management is that most insect pests are secondary to underlying tree stress. A healthy tree has physical and chemical defenses that suppress or resist pest attacks. Stressed trees — from drought, soil compaction, root damage, disease, or poor site conditions — are vulnerable.
When a tree has a significant pest problem, the first question should be: why is this tree stressed? Addressing the underlying cause often resolves the pest pressure better than treatment alone.
Scale Insects
Scale insects are among the most common and underdiagnosed pests of landscape trees in North Florida. They feed by inserting a stylet into plant tissue and extracting plant sap. Most species secrete a waxy coating that makes them look like part of the bark rather than an insect.
What to look for:
- Crusty, bumpy, or discolored patches on bark and stems
- Sooty mold — a black fungal coating on leaves and branches below where scales feed. The scales excrete honeydew, which the sooty mold grows on. This is often the first thing noticed.
- Yellowing or reduced growth
- Sticky feel on leaves and branches (honeydew)
Common species in North Florida:
- Florida red scale — attacks a range of ornamental trees
- Brown soft scale — common on hollies, magnolias, camellias
- Euonymus scale — on euonymus and related plants
- Tea scale — on camellias and hollies
Management: Light infestations on healthy trees often don't require treatment — natural predators (beneficial insects, birds) can control scale populations. Heavy infestations, or infestations on stressed trees, may warrant horticultural oil applications (dormant oil or summer oil, applied carefully to avoid phytotoxicity) or systemic insecticides for severe cases.
Fall Webworm
Fall webworm (Hyphantria cunea) is one of the most visible tree pests in North Florida — it produces conspicuous white silk webs at the branch tips of a wide range of deciduous trees in late summer and fall. Pecan, persimmon, and many other trees are commonly affected.
What to look for:
- White silk webbing enclosing branch tips and leaves
- Hairy caterpillars inside the web (pale with tufted hair)
- Typically appears late summer through fall
Damage assessment: Fall webworm is rarely a serious health threat to established trees. Infestations look alarming but typically affect a small percentage of the total leaf area. A healthy tree defoliating partially in August-September from fall webworm still has time to complete the season and will re-leaf normally next spring.
Management: For small trees or low branches, physical removal of webs (cut the affected branch out, or use a pole to open the web and allow natural predators access) is effective. Treating large trees for fall webworm is usually not warranted — the cosmetic damage doesn't justify insecticide application in most cases.
Aphids
Aphids are small soft-bodied insects that cluster on new growth and extract plant sap. North Florida hosts numerous aphid species; they're most active in spring and fall when tender new growth is available.
What to look for:
- Clusters of small soft-bodied insects (various colors — green, black, yellow, depending on species) on stems and undersides of leaves
- Curled or distorted new growth
- Sooty mold on leaves (from aphid honeydew)
- Ants tending aphid colonies (ants protect aphids and harvest honeydew)
Management: Aphid populations are heavily controlled by natural predators — ladybugs, lacewings, parasitic wasps. On established trees, aphid pressure is usually self-limiting unless predators have been disrupted by pesticide applications. For valuable young trees or ornamentals with severe infestations, targeted insecticidal soap applications are effective and less disruptive to beneficials than synthetic insecticides.
Tent Caterpillars (Eastern Tent Caterpillar)
Eastern tent caterpillar (Malacosoma americanum) builds silken tents at branch forks (distinguishing it from fall webworm, which builds webs at branch tips) in early spring.
What to look for:
- Silken tent structures at branch forks (not branch tips)
- Dense concentrations of caterpillars inside the tent in morning and evening
- Defoliation of branches adjacent to the tent
- Common hosts: wild cherry, crabapple, ornamental cherry, apple
Management: Eastern tent caterpillar typically doesn't seriously harm established trees — defoliated trees re-leaf in the same season. Physical removal (prune out the tent, destroy it) in early stages is effective and sufficient in most cases.
Bark Beetles (Secondary Pests)
See our full pine tree care guide for specific information on bark beetles affecting pines. The key principle applies to all bark beetle situations: they're secondary pests that attack stressed or declining trees, not primary killers of healthy ones.
Emerald Ash Borer (Spreading Threat)
Emerald ash borer (Agrilus planipennis) has devastated ash tree populations across the Eastern US and is continuing to spread southward. It has been confirmed in Florida.
If you have ash trees (Fraxinus spp.) on your property:
- Green ash and water ash are common in North Florida landscapes
- EAB kills ash trees by destroying the cambium layer, cutting off water and nutrient transport
- Symptoms: crown dieback from the top down, S-shaped galleries visible under bark, D-shaped exit holes, increased woodpecker activity
- Treatment options exist (systemic insecticides applied to soil or injected into trunk) but must be applied preventively — treatment of already-infested trees has limited effect
The Florida Forest Service and UF IFAS Extension monitor for EAB spread. If you observe symptoms in ash trees, report them.
Questions about tree pests in Tallahassee? Call (850) 570-4074 or request an inspection online.