5 Common Tree Insects of Lancaster County: How to Spot Them and What to Do

Tree pests cause millions of dollars in damage across Pennsylvania annually, with Lancaster County particularly affected by five destructive species. Whether you’re dealing with active damage or want to prevent future problems, understanding these common tree insects – their behavior, signs of infestation, and treatment options – is crucial for protecting your trees.

Key Takeaways:

• The emerald ash borer can kill ash trees within a few years by disrupting their ability to transport water and nutrients.
• Spotted lanternflies primarily target tree of heaven, grape vines, and maple trees in Lancaster County, leaving behind honeydew that attracts other insects and promotes fungal growth.
• Hemlock woolly adelgid, identifiable by white, waxy masses on branches, can be managed year-round with insecticide treatments to prevent damage.
• Scale insects, both soft and armored, can cause yellowing, wilting, and branch dieback; severe infestations may require an Integrated Pest Management (IPM) approach for control.
• Spongy moths (formerly known as gypsy moths) primarily target oak trees but can attack various species; management options include insecticides, tree banding, and egg mass destruction.

5 Common Tree Pests Southeastern Pennsylvania Residents Should Know About

Lancaster County is known for its beautiful landscapes, but it’s also home to a variety of tree-damaging insects. As the weather warms and trees come back to life, so do these pests – many of which can weaken or even kill trees if left unchecked. Knowing what to watch for can help you protect your trees before the damage becomes severe.

1. Emerald Ash Borer

Emerald ash borer (EAB) is an invasive species native to Asia that arborists first detected in Pennsylvania in June 2007. Though initially found in the western part of the state, EAB quickly spread throughout Pennsylvania and is present in every county, including Lancaster County.

“As an invasive species, EAB has no natural predators or counters to keep its population in check. Instead, it can spread and reproduce unimpeded and continue killing our native ash trees. I can’t even count how many calls we’ve had to either try and save an ash tree or take one down. It’s a really tough situation.” – Erik Johnson, ISA Certified Arborist at Arborist Enterprises

The damage from EAB is extreme, as this insect can kill an ash tree in a few years. EAB larvae feed on the inner bark of the tree. This impedes a tree’s ability to transport food and water from the roots to the canopy, eventually killing the tree.

Ash trees killed by EAB are notoriously brittle and dangerous to work with. Their internal damage makes them prone to breaking, and they can put your family and property at risk.

Prevention and Treatment of Emerald Ash Borer

Prevention is often the most effective way to protect your ash trees from Emerald Ash Borer (EAB). A systemic insecticide, injected directly into the trunk of the tree, can offer protection when applied by an expert during the appropriate season.

Ash trees with severe EAB infestations will likely not survive, and removal may be necessary to ensure the safety of your property.

2. Spotted Lanternfly

The spotted lanternfly (SLF) has become a hot-button topic since arborists first detected it in Pennsylvania in 2014. Since then, the invasive insect has spread throughout most of southern and eastern Pennsylvania, and it is a common sight in Lancaster County every year.

The spotted lanternfly feeds on plant sap, weakening trees and, in some cases, even killing them. While it prefers the non-native tree of heaven, it also attacks many important Pennsylvania tree species that play a key role in the state’s economy, including:

• Grapevines
• Black walnuts
• Birches
• Maples

When SLF feeds on trees, it leaves behind honeydew. Honeydew is a sweet substance that attracts other insects and can cause fungi to grow on landscape trees.

PRO TIP: Want to learn more about SLF and the threat it poses to our area? Check out our in-depth article on spotted lanternflies in Lancaster County.

Prevention and Treatment of Spotted Lanternfly

In general, insecticides may not be required for controlling spotted lanternfly (SLF) if the population is manageable. However, treatment options should still be considered based on the severity of the infestation. Physical control methods can be effective, including:

• Scraping and smashing any egg masses you see
• Using tree traps
• Stomping and swatting adults

Southeastern Pennsylvania is in the SLF quarantine zone. Which means, if you plan to take a trip to an area out of the quarantine zone, take precautions to avoid spreading SLF. Check your vehicle and any items you bring for signs of SLF, as the insect travels well. Adults can remain on cars going up to 65 miles per hour, and egg masses can blend into mud on your tires.

3. Hemlock Woolly Adelgid

The hemlock woolly adelgid has caused severe damage to eastern hemlocks across Pennsylvania. If you have hemlocks in your yard, it’s important to keep an eye out for signs of an infestation.

These tiny insects attack by piercing the needles and sucking out plant fluids, which weakens the tree. Even a moderate infestation can cause significant damage, and severe cases lead to dieback or even tree death.

Fortunately, HWA is easy to spot. Look for white, waxy masses on the undersides of branches – these will stay on the tree through winter, giving you plenty of time to catch and treat the problem before it spreads.

Treatment and Prevention of Hemlock Woolly Adelgid

Insecticides can be used to treat hemlock woolly adelgid infestations on hemlocks. Treatment options are available year-round to ensure effective management of the pest.

4. Scale Insects

Scale insects is an umbrella term for many tree insects that target Pennsylvania trees. In general, there are two main kinds of scale insects:

• Soft Scales: Soft scales are typically larger and more rounded than armored scales. They secrete honeydew while feeding, which can lead to fungal growth like sooty mold. While soft scales can cause stress to trees, they usually don’t result in tree death unless the infestation is severe.
• Armored Scales: These scales are smaller and flatter, and it is possible to remove their protective cover. They do not excrete honeydew like soft scales. Under heavy infestation, armored scales are more likely to kill trees.

Many homeowners ignore scales because they look like bumps on their trees. The females will feed on leaves, causing a few noticeable symptoms:

• Yellowing leaves
• Wilting leaves
• Honeydew on leaves or beneath the tree
• Black mold growing on the honeydew
• Premature leaf drop
• Branch dieback

Scale insects usually don’t kill trees unless the infestation is severe.

Most types of scale only target one specific tree species and won’t spread to others. However, during their crawler stage, they move in search of new leaves to feed on. Wind and rain can also carry them to nearby trees, where they latch on and begin feeding.

Treatment and Prevention of Scale of Insects

A comprehensive Integrated Pest Management (IPM) approach is often best for dealing with scale insects. Keeping your plants generally healthy will increase resistance to scale attacks, and introducing natural predators can help control the scale population.

Arborists typically don’t recommend insecticides for dealing with scale unless the problem becomes intolerable. Spraying insecticides requires precise timing, as it is only really effective during the crawler stage and not after they develop their protective covering.

5. Spongy Moth

Oak trees face numerous threats in our ecosystem, including spongy moths (previously known as gypsy moths). While oaks are the most famous and most common target for spongy moths, they attack many other trees, including:

• Apple
• Willows
• Pines
• Hemlock
• Birches
• Aspens

Spongy moth caterpillars feed on the foliage of their host plant, defoliating the plants in the spring and early summer. If the infestation is severe enough, this defoliation can kill a tree over a few seasons, as trees depend on their leaves for photosynthesis.

How to Manage Spongy Moth in Lancaster County

Spongy moths are damaging tree insects and require prompt action to protect your trees. A few of the management options available to homeowners include:

• Insecticides: Insecticides can help control severe infestations and prevent excessive leaf loss. For the best results, we recommend having a professional apply targeted treatments when caterpillars are most active, usually in May.
• Banding: Burlap banding provides a shelter where caterpillars will rest, allowing you to easily find and remove them. You can either smash them or dump them into a bucket of soapy water. Sticky banding with an adhesive can also trap caterpillars and protect your leaves. Just ensure you remove any banding by the summer.
• Destroy Eggs: From October to April, you can spot egg masses on trees. To remove them, scrape the eggs into soapy water – don’t try to smash them, as this won’t stop them from hatching. You can also apply horticultural oils to reduce the hatch rate and help control the infestation.

FAQs About the Common Tree Insects of Our Area

Tree insects can be one of the most frustrating aspects of caring for Southeastern Pennsylvania landscapes. We’ve compiled some common questions from our clients about tree pests and how to protect their property.

How can I prevent damage from the typical tree pests of Lancaster County?

You can prevent damage from typical tree insects by keeping your trees healthy with watering, mulching, and pruning. Other things you can do include:

• Have an arborist apply preventive insecticides
• Diversify the species on your property
• Look for symptoms of insect attacks

How often should I have a professional inspect my trees for signs of insect activity?

We recommend yearly inspections of your property by an ISA Certified Arborist. They can examine your trees, look for signs of any pest damage, and provide recommendations for treatment options.

Are there alternatives to insecticides for my trees?

Yes, there are natural methods for controlling insect populations. An Integrated Pest Management (IPM) approach to tree care focuses on maintaining healthy landscape trees and using less-invasive methods whenever possible. Our team prefers to avoid insecticides unless necessary and always applies targeted treatments to address specific issues.

What are some common signs of a pest infestation?

Some typical signs to watch out for that may indicate a problem include:

• Wilting leaves
• Discolored leaves
• Increased insect activity
• Premature leaf drop
• Dead patches on the canopy

Protect Your Lancaster County Trees with Expert Care from Arborist Enterprises

Lancaster’s trees face unique challenges from destructive pests, but you don’t have to tackle these problems alone. Our ISA Certified Arborists at Arborist Enterprises bring over 30 years of local experience in identifying and treating tree pest infestations. We understand which treatments work best in our specific climate and soil conditions.

Don’t wait until pest damage becomes severe. Call us at 717-393-7602 or request an estimate online to protect your valuable trees today.