Chewed leaves, sticky residue, and thinning branches can leave you wondering what is happening to your trees. Several Maryland tree pests cause these changes, but the level of concern depends on the pest, the amount of damage, and the tree’s condition.
Some pests mainly affect a tree’s appearance, while others can cause lasting decline. Knowing what to look for can help you recognize a problem and understand when professional attention is needed. Here are eight pests Maryland homeowners may encounter, along with the signs and risks associated with each.
Tree Pests Maryland Homeowners Should Recognize
Aphids
Aphids feed on plant sap and can cause curled or yellowing leaves. They leave behind a sticky liquid called honeydew, which may collect beneath trees and support black mold growth. Small populations usually cause little harm, and helpful insects often keep them under control.
Eastern Tent Caterpillars
Silk tents where cherry or crabapple branches meet during spring often indicate eastern tent caterpillars. They eat leaves but usually do not seriously harm established trees. Small trees that lose their leaves repeatedly are more vulnerable.
Spongy Moth Caterpillars
Spongy moth caterpillars feed on oaks and other trees, generally in May and June. Older caterpillars have pairs of blue and red spots along their backs. They do not build tents. Losing most of their leaves year after year can weaken or kill affected trees.
Spider Mites
Spider mites are tiny relatives of spiders that cause pale speckles on leaves. Large numbers may produce fine webbing. Some are active in warm weather, while others prefer cooler conditions. Confirm the cause before treating, since helpful mites may also be present.
Bagworms
Bagworms carry bags covered with pieces of leaves that can resemble small cones. They often damage arborvitae, juniper, cedar, spruce, and pine. Heavy feeding can permanently damage or kill these evergreens. Check for small bags in spring, when young caterpillars are easier to control.
Japanese Beetles
These metallic green beetles with coppery-brown wing covers eat leaves during summer. Their young, called grubs, mainly feed on lawn roots. Handpicking beetles from plants you can safely reach may help. Avoid beetle traps near vulnerable plants, as they can attract more beetles and increase damage.
Cicadas
Female cicadas cut small slits in twigs to lay eggs, sometimes causing branch tips to wilt or break. Healthy, mature trees usually tolerate this damage. Young trees are more vulnerable when large numbers of periodical cicadas emerge and may benefit from properly fitted insect netting.
Emerald Ash Borer
Emerald ash borer can kill ash trees when its young, called larvae, feed beneath the bark. Signs include dying upper branches, new shoots along the trunk, and small D-shaped holes in the bark. Arrange an assessment promptly to discuss whether treatment or removal is appropriate.
What to Do If You Suspect Tree Pest Damage
fYellow leaves or dying branches do not always mean pests are responsible. Too little water, poor drainage, and damaged roots can cause similar changes. Recording what you see can help identify the cause.
- Photograph the tree and damaged areas. Include close-ups of insects, webbing, bags, or holes in the bark.
- Record when changes began. Note whether damage is spreading or has appeared in previous years.
- Consider recent yard changes. Digging, construction, and changes in drainage can affect tree health.
- Watch for patterns. Notice whether damage affects one branch, the whole tree, or nearby plants.
dAvoid spraying simply because insects are present. If treatment is recommended, follow the product label and make sure it is suitable for the plant and pest.
Get Guidance for Damaged Trees in Maryland
If you are concerned about changes in a tree’s health, Nelson Tree Specialist can assess its condition and discuss appropriate next steps.
The company provides tree care services, pruning, removal, and evaluations of tree stability for Maryland properties. Contact us to discuss your concerns and arrange an evaluation.