Honeylocust Tree Health: Mossy Patches and Green Bugs Explained

Assessing the Symptoms

A 16-year-old honeylocust with mossy green patches at the base and tiny green bugs on the foliage is showing signs of two common but distinct issues: lichen growth and an insect infestation—likely aphids or leafhoppers.

What Are the Mossy Green Patches?

The green, mossy material on the trunk base is typically lichen—a symbiotic organism of fungus and algae. Lichens are not parasitic; they simply use the bark as a surface to grow. Their presence often indicates thin canopy cover or slow growth, but they do not harm the tree directly.

Identifying the Little Green Bugs

The small green insects are probably aphids or leafhoppers, both common on honeylocusts. They feed on sap, causing leaf curling, yellowing, and honeydew buildup. Heavy infestations can stress the tree and attract sooty mold.

Concerns About Recent Pruning

Improper pruning—especially tearing bark or leaving stubs—can create entry points for pathogens like Hypoxylon canker, a serious fungal disease. Ensure cuts are clean, made with sharp tools, and just outside the branch collar. Avoid pruning during wet weather.

Recommended Actions

• Monitor the insects: If populations are low, natural predators may control them.
• Use targeted treatments: Insecticidal soap, neem oil, or a systemic like imidacloprid (e.g., Merit) can reduce aphids.
• Inspect pruning wounds: Check for signs of decay, oozing, or fungal conks.
• Improve tree vigor: Water during drought, mulch properly (2–3 inches, not against trunk), and fertilize if soil tests indicate deficiency.

When to Call an Arborist

If you see dead branches, cracked bark, or fungal fruiting bodies, seek professional evaluation. Honeylocusts are resilient but vulnerable to borers and cankers when stressed.