While most tree bugs are harmless, some are dangerous. Identifying these harmful insects is important for protecting trees and property inhabitants. This article details the threats certain tree bugs present and offers guidance on management.
Understanding the Threat
Tree bugs can harm trees and pose risks to humans and pets. Some insects directly harm trees by feeding on their tissues or disrupting their structural integrity.
Certain bugs, known as borers, tunnel into tree trunks, stems, and roots, whose larvae feed on the tree’s inner workings. This internal damage hinders the tree’s ability to absorb water and nutrients, leading to canopy dieback or tree death. Other insects, like defoliators, consume leaves, while sap-suckers extract plant juices, depriving trees of resources, causing yellowing leaves, stunted growth, or sooty mold from their sticky excretions.
Bites or stings can cause localized pain, swelling, or allergic reactions. Certain caterpillars have irritating or venomous hairs that, upon contact, can embed in the skin, leading to rashes, intense itching, and inflammation. Airborne hairs can also cause respiratory issues. Pets may experience similar skin irritations or symptoms if they contact or ingest these insects.
Key Dangerous Tree Bugs to Know
The Emerald Ash Borer (EAB) is a metallic green beetle, 3/8 to 5/8 inches long, native to Asia. Its larvae create S-shaped tunnels, called galleries, under ash tree bark, disrupting water and nutrient flow, typically leading to tree death within a few years. Signs of EAB infestation include:
- Canopy thinning
- Growth of secondary shoots from the trunk
- Splitting bark
- D-shaped exit holes (about 1/8 inch in diameter) where adults emerge
- Increased woodpecker activity as they forage for larvae
The Browntail Moth caterpillar is active from April to July. These caterpillars are brown with a broken white stripe on each side and two red-orange spots on their hind end, covered in tiny, barbed hairs. Their microscopic hairs contain a toxin that causes a rash similar to poison ivy, characterized by red, itchy bumps lasting from a few days to weeks. Airborne hairs can also lead to respiratory problems.
The Gypsy Moth, now called the Spongy Moth, is an invasive species whose larvae are heavy defoliators. These caterpillars are hairy, growing up to 2 inches long, with five pairs of blue spots and six pairs of red spots along their backs. They feed on hundreds of plant types, including oak, elm, and maple. Severe infestations can completely strip trees of their leaves. While healthy trees can sometimes withstand a single defoliation, repeated attacks weaken them, making them vulnerable to other pests and diseases, and can ultimately lead to tree death, especially for evergreens. Signs include chewed leaves and hairy, tear-shaped egg masses on tree trunks or outdoor surfaces.
The Spotted Lanternfly, an invasive planthopper from Asia, feeds on the sap of a wide range of fruit, woody, and ornamental trees. Adults have distinctive wings (brown with black spots, bright red with black spots) and a yellow and black-striped body. As they feed, they excrete honeydew, a sticky, sugary substance that promotes black sooty mold growth on trees and surrounding surfaces. While feeding may not directly kill trees, it weakens them, increasing their susceptibility to other stressors. Oozing sap and sooty mold are common indicators of their activity.
Other stinging caterpillars include:
- Puss Caterpillar
- Saddleback Caterpillar
- Io Moth Caterpillar
- Buck Moth Caterpillar
These often brightly colored or uniquely shaped caterpillars have hollow, venomous spines or hairs that cause immediate, intense burning, pain, and swelling upon contact.
Safeguarding Your Home and Trees
Protecting your home and trees from dangerous bugs involves preventative measures and timely intervention. Maintaining overall tree health is a strong defense, as healthy trees better withstand pest attacks. This includes proper watering, necessary fertilizing, and applying mulch around tree bases to retain moisture and provide nutrients. Regular pruning of dead or diseased branches also removes potential breeding grounds and improves tree vigor.
Routine tree inspection is important for early pest detection. Look for signs like:
- Discolored or chewed leaves
- Holes in bark
- Sticky substances (honeydew)
- Unusual growths
Checking outdoor items, especially in areas with invasive species like the Spotted Lanternfly, can also prevent their spread. When working in areas with stinging caterpillars or other irritating insects, wear long sleeves, gloves, and other protective clothing to prevent direct contact.
Knowing when to seek professional help is important. If you notice signs of a significant infestation, widespread tree damage, or a bug causing a severe reaction, contact a certified arborist or pest control professional. Arborists can identify the pest, assess damage, and recommend treatment options. Early professional intervention can often save a tree and advise on safe removal of hazardous insects or infested materials.