Common Insects That Threaten Your Trees and Landscape

Your trees and plants are a valuable part of your property - but they're not just facing diseases. Insects can also cause significant damage, sometimes going unnoticed until it's too late. Understanding which pests are common in southeastern Wisconsin, the signs to watch for, and how to manage them is key to keeping your landscape healthy and thriving.

Below are some of the pests we most often see, what they do, and how to identify them early.

Spongy Moths (formerly Gypsy Moth)

Commonly affects: Oaks and other hardwood trees

They Spongy Moth is notorious for defoliating trees during outbreak years. While a single year of defoliation might not kill a mature tree, repeated attacks weaken trees over time, making them more susceptible to disease and other pests.

Signs to watch for:

• Catepillars crawling on leaves and branches in spring

• Thin or missing foilage

• Brown, shriveled leaves and webbing in extreme cases

Emerald Ash Borer

Commonly affects: Ash trees

Emerald Ash Borer is a metallic green beetle that has devastated ash populations across the Midwest. Larvae feed under the bark, disrupting the tree's vascular system and eventually killing it. Early detection is critical, but often the damage isn't noticeable until decline is advanced.

Signs to watch for:

• D-shaped exit holes in bark

• Branch dieback starting at the top of the tree

• Thinning canopy and bark splitting

Japanese Beetle

Commonly affects: Hundreds of plant species including roses, linden trees, and turf

Japanese Beetles feed on leaves, flowers, and fruit, leaving behind a characteristic skeletonized appearance. Larvae (grubs) damage grass roots, affecting lawns. Heavy infestations can weaken plants and make them more vulnerable to other stressors.

Signs to watch for:

• Metallic green beetles feeding on leaves and flowers

• Skeletonized foilage

• Grubs in the soil during summer affecting turf

Two-Lined Chestnut Borer

Commonly affects: Oaks, particularly stressed or weakened trees

This bark beetle targets trees already under stress (drought, root damage, or previous pest/disease damage). Larvae feed under the bark, interupting nutrient and water flow, which can lead to branch dieback and tree death.

Signs to watch for:

• Yellowing or thinning foilage

• Branch dieback from the top down

• Small bark tunnels visible on closer inspection

Scale Insects

Commonly affects: Maples, dogwoods, boxwoods, and many ornamental trees and shrubs

Scale insects attach to branches and leaves, feeding on sap. Heavy infestations weaken plants, reduce growth, and sometimes kill branches. They also excrete honeydew, which encourages sooty mold.

Signs to watch for:

• Tiny, immobile bumps on stems or leaves

• Yellowing or dropping leaves

• Sticky residue or black sooty mold

Managing Tree and Plant Pests

Early detection and proactive care are essential to managing pests and keeping your landscape healthy. Your Personal Gardener & Arborist offers comprehensive Plant Health Care and Pest Control Services, including:

• Professional pest identification

• Targeted insecticidal treatments

• Soil and tree care to reduce stress and susceptibility

• Long-term monitoring and preventative care

Whether you're noticing the first signs of an infestation or want a preventative approach, our experts develop a customized plan to protect your trees, shrubs, and lawn.

Concerned about pests in your landscape?

Contact YPGA today to schedule a Plant Health Care or Pest Control consulation and keep your property thriving year-round.

https://www.ypgausa.com/contact