If you’ve spent any time looking after your trees, you’ve probably seen some unwelcome visitors. While a few insects are part of a healthy ecosystem, some pests can do real damage to your trees if left unchecked. Knowing how to spot signs of pest activity can help prevent long-term damage. Here’s a breakdown of some of the most common tree pests in Illinois, how they affect your trees, and what steps you can take to keep your landscape healthy.
What are tree pests?
Tree pests are insects or other organisms that feed on or infest trees, often causing damage to the bark, leaves, roots, or inner structure of the tree. Some are native to our area and typically don’t cause serious harm in small numbers. Others, especially invasive species, can lead to rapid decline or even death if left untreated.
Emerald Ash Borer (EAB)
The emerald ash borer is a shiny green beetle that has decimated countless ash trees across Illinois since it first appeared in the early 2000s. The larvae burrow under the bark, cutting off the tree’s ability to transport water and nutrients, which slowly kills it.
Signs to watch for:
- D-shaped holes in the bark
- Thinning canopy or dead branches at the top of the tree
- Splitting bark
- Increased woodpecker activity
What to do: If you still have healthy ash trees, preventive treatments can help protect them. If the tree is already heavily infested, removal is often the best option. Regular inspections by a certified arborist can catch EAB before it’s too late.
Japanese Beetles
These shiny beetles may look harmless, but they can quickly skeletonize leaves, leaving your trees looking like lace doilies. They’re especially fond of linden, crabapple, and birch trees but feed on the leaves of over 300 tree and shrub species.
Signs to watch for:
- Skeletonized leaves (only the veins remain)
- Clusters of beetles feeding on foliage during summer
What to do: Handpicking beetles and using traps can help on smaller trees. For larger infestations, professional treatments may be needed to protect the tree’s canopy. It’s best to act early in the season before populations explode.
Gypsy Moth (Spongy Moth)
The gypsy moth is an invasive species whose caterpillars feed primarily on oak leaves. Large infestations can defoliate entire trees, leaving them vulnerable to other issues.
Signs to watch for:
- Egg masses on bark or outdoor surfaces
- Caterpillars with blue and red dots on their backs
- Chewed or missing leaves, especially in late spring
- Bare branches in summer
What to do: These moths can weaken trees over time, especially with repeated infestations. Scraping off egg masses in the fall and using pheromone traps in the spring can help keep the population under control.
Scale Insects
These tiny bugs often resemble small bumps on twigs or leaves, but they can cause significant problems. Scale insects suck sap from trees and secrete a sticky substance known as honeydew, which can lead to the growth of sooty mold and ultimately weaken the trees over time.
Signs to watch for:
- Sticky residue on leaves or ground
- Black mold on leaves or bark
- Small, dome-like bumps on branches
- Yellowing leaves or stunted growth
What to do: Scale can be tough to manage without expert help. Arborists may recommend horticultural oils or systemic treatments, depending on the scale of the species and severity.
Bagworms
These caterpillars create silken bags covered in bits of needles and bark. They’re most found on arborvitae, spruce, and junipers. Bagworms can strip a tree bare if not addressed.
Signs to watch for:
- Hanging silk bags that look like small pinecones
- Browning or defoliated needles
What to do: For small infestations, handpick and destroy visible bags in fall or winter. For larger infestations, treatment by a professional arborist is often necessary to prevent spread.
Prevention: Keeping Tree Pests In Check
Preventing tree pests is often easier than treating them after they appear. Regular tree inspections are one of the best ways to catch pest problems early before they do severe damage. It’s always a good idea to bring in a certified arborist for a closer examination. Proper watering, mulching, and pruning make trees less vulnerable to pests. Overwatering, drought, and soil compaction can weaken trees, making them more susceptible to pests.
We are familiar with the local pests, and more importantly, we know how to deal with them effectively. Our certified arborists are trained to identify signs of infestation and create targeted treatment plans. If you need help with tree pests, don’t wait until it’s too late. Contact Abbott Tree Care today to schedule a consultation and learn how we can help protect your trees.
