A handful of insects, several of them invaders from overseas, do most of the serious damage to trees in Virginia.
The best defense against almost all of them is a healthy, well-watered tree. Many of the worst pests go after trees already weakened by drought, root damage or poor planting.
Emerald Ash Borer
This small, metallic green beetle from Asia has killed millions of ash trees across the country. It was confirmed in Virginia in 2008 and is now found in every region of the state. It attacks all Virginia ash species, including green ash and white ash.
Signs
- A thinning canopy that dies back from the top down
- Small D-shaped exit holes in the bark, about an eighth of an inch across
- Patches of light-colored bark where woodpeckers have stripped the outer layer hunting larvae
- Sprouts growing from the trunk and base
- S-shaped tunnels under loose bark
What to Do
- Protect healthy, valuable ash trees before they're infested. Systemic insecticides work well when started early. For trees about 15 inches across or smaller, homeowner soil drenches containing imidacloprid can be applied in spring. Larger trees need trunk injections from a licensed professional.
- Check for cost-share help. The Virginia Department of Forestry runs a program that can cover part of the cost of treating qualifying ash trees.
- Remove dead ash promptly. Ash killed by the borer dries out and becomes brittle quickly. It can drop large limbs or snap without warning, and it gets more dangerous to cut the longer it stands.
- Don't move firewood. Buy it where you'll burn it.
Southern Pine Beetle and Pine Engraver Beetles
These native bark beetles attack loblolly and other pines, especially trees stressed by drought, lightning strikes, root damage or construction. In outbreak years, they can kill groups of pines quickly across the Coastal Plain.
Signs
- Small, popcorn-like lumps of sap (pitch tubes) on the bark
- Reddish boring dust in bark crevices and at the base of the tree
- Needles fading from green to yellow to reddish brown, often across the whole crown at once
- Nearby pines dying in a growing cluster
What to Do
- Remove infested pines quickly, before beetles move to neighboring trees. By the time a pine turns fully red, the beetles have often left, but the dead tree is still a hazard.
- Keep pines healthy. Avoid root damage, soil fill and trenching near them, and water during long droughts.
- Remember that some needle drop in fall is normal. Pines shed their oldest inner needles every year.
Spotted Lanternfly
This invasive planthopper was first found in Virginia in Winchester in 2018. As of 2025, it had established populations in 67 Virginia cities and counties, and the state ended its quarantine because the insect had spread too widely to contain. Its favorite host is the invasive tree-of-heaven, but it also feeds on maples, black walnut, willows and grapevines.
Signs
- Adults in late summer and fall: about an inch long, with gray, black-spotted front wings and bright red hind wings
- Young nymphs in spring and summer: black with white spots, turning red with white spots later
- Mud-like, gray egg masses on trunks, stones, vehicles and outdoor furniture from fall through spring
- Sticky honeydew and black sooty mold on and under trees
What to Do
- Scrape egg masses into a bag or jar with rubbing alcohol or hand sanitizer.
- Remove tree-of-heaven from your property. Cut stems sprout back hard, so treatment of the stump or the root system is usually needed.
- Check your vehicle before leaving infested areas.
- If you see one where it isn't established yet, including much of Hampton Roads, report it to the Virginia Department of Agriculture and Consumer Services.
Hemlock Woolly Adelgid
This tiny, aphid-like insect from Asia has killed large numbers of eastern hemlocks, mostly in western and northern Virginia. Look for small, white, cottony tufts at the base of needles on the undersides of branches from late fall through spring. Systemic insecticides and horticultural oil can protect landscape hemlocks when applied before the tree declines badly.
Bagworms
Bagworms build spindle-shaped bags of silk and bits of foliage that hang from branches like small pine cones. They strip needles from eastern red cedar, bald cypress, arborvitae and other evergreens, and heavy infestations can kill a tree.
- From fall through early spring, pick off and destroy the bags. Each female bag can hold hundreds of eggs.
- In late May and June, when the new caterpillars and bags are still small, sprays containing Bt (Bacillus thuringiensis) work well.
Spongy Moth
Formerly called gypsy moth, this caterpillar defoliates oaks and other hardwoods in outbreak years, mostly in northern and western Virginia. Healthy trees usually releaf the same summer, but several years of defoliation in a row, especially combined with drought, can lead to decline.
Scale, Aphids and Sooty Mold
If leaves, cars or patios under a tree get sticky and turn black, sap-feeding insects are usually the cause. Tulip poplar, magnolia and maples often host scale insects and aphids that drip honeydew, which then grows black sooty mold. It's rarely deadly. Lady beetles and other natural enemies usually keep it in check. For heavy scale, dormant-season horticultural oil helps.
Borers That Follow Stress
Some native insects mostly attack trees already in trouble:
- Two-lined chestnut borer attacks oaks weakened by drought, defoliation or root damage.
- Dogwood borer gets into dogwoods through mower and trimmer wounds at the base.
- Ambrosia beetles bore into stressed and newly planted trees, pushing out tiny toothpick-like strands of sawdust.
For all of these, prevention means water in drought, mulch instead of lawn at the base, and no wounds from lawn equipment.
Where to Get Help
Your local Virginia Cooperative Extension office can identify insects from samples or photos and recommend current treatments. If a pest has already killed or badly weakened a tree near your home, have it assessed for safety.