managing invasive species
Managing Invasives
Twin Lakes is home to diverse ecosystems that require thoughtful stewardship to maintain their health and balance. Invasive species—including certain plants, pests, and tree diseases—threaten biodiversity, water quality, and soil stability. This guide focuses on the specific challenges faced by our community in recent years, providing practical, non-chemical solutions for managing these threats.
Why Does Management Matter?
Unchecked invasive species weaken native plant populations, disrupt habitats, and contribute to tree decline. Invasive pests such as the spongy moth and woolly adelgid threaten forests by damaging foliage and reducing resilience to disease. Similarly, invasive plants like Japanese stiltgrass and Japanese barberry spread aggressively, altering soil composition, outcompeting native species, and disrupting local ecosystems.
In addition to invasive pests and plants, tree diseases like oak wilt, mountain laurel disease, and eastern white pine disease pose significant threats to Twin Lakes’ forests. These conditions weaken trees, reduce biodiversity, and compromise the health of riparian buffers, which are vital for water quality and erosion control.
Our Approach
We prioritize sustainable and environmentally responsible management strategies. Instead of relying on chemical treatments, we focus on manual removal, habitat restoration, and preventative measures to control invasive species while protecting the integrity of the ecosystem.
Read below for information about the invasive plants, pests, and diseases currently of concern in our community and strategies for dealing with them. To jump to a specific section, please click on the Learn More button for the pest of interest.
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Japanese Barberry
Japanese barberry (Berberis thunbergii) is an invasive shrub that spreads aggressively, disrupting forests and riparian areas.
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Japanese Stiltgrass
Japanese stiltgrass (Microstegium vimineum) is an invasive grass rapidly spreading in disturbed environments, along roadside ditches and trails
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Spongy Moth
Spongy moths (Lymantria dispar) are an invasive species that can cause serious damage to trees during outbreak years.
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Hemlock Woolly Adelgid
Hemlock Woolly Adelgid (Adelges tsugae) an invasive insect that weakens and eventually kills Hemlock trees, the state tree of Pennsylvania.
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Spotted Lanternfly
The Spotted Lanternfly (Lycorma delicatula) feeds on plant sap from a wide range of crops, ornamental plants and various hardwood trees, damaging them by stressing and weakening the plants.
Japanese Barberry
Japanese barberry (Berberis thunbergii) is an invasive shrub that spreads aggressively, disrupting forests and riparian areas. Once widely sold in nurseries and recommended as a deer-resistant shrub, it has now escaped cultivation, overtaking native vegetation and increasing tick populations, raising concerns about Lyme disease. It is growing in dense thickets in many areas in our community and throughout the forests along the northern sections of Twin Lakes Road.
In October 2021, the PA Department of Agriculture added Japanese barberry to the noxious weed list, banning its sale and cultivation.
Removal & Control Strategies
Manual Removal
Hand-Pulling & Digging: Remove entire plants, including roots, to prevent regrowth. Best done when soil is moist.
Cutting & Mowing: Weakens plants over time but does not eliminate root systems.
Bag & Dispose: Seal removed plants in trash bags; do not compost, as seeds and roots can regenerate.
Non-Toxic Control
Smothering: Cover affected areas with heavy tarps or mulch to block sunlight and suppress regrowth.
Native Replanting: Introduce fast-growing native species to restore biodiversity and prevent re-infestation.
Preventing Future Growth
Regular Monitoring: Inspect trails, roadsides, and riparian areas for regrowth.
Remove Before Berries Form: Prevent seed spread by eliminating plants before fruiting.
Limit Soil Disturbance: Avoid excessive clearing—barberry thrives in disturbed environments.
Clean Equipment: Seeds and fragments cling to boots and tools—clean gear after working in infested areas.
For deer-resistant native alternatives, consider:
Winterberry holly (Ilex verticillata)
Spicebush (Lindera benzoin)
Arrowwood viburnum (Viburnum dentatum)
For more information and additional control strategies:
Japanese Stiltgrass
Japanese stiltgrass (Microstegium vimineum) is an invasive grass rapidly spreading in disturbed environments, along roadside ditches and trails. It spreads exclusively by the many seeds it produces, transported by water, or attached to footwear, vehicles or any other contaminated object. Following winter storms between 2018 and 2021, its expansion accelerated in Twin Lakes, where exposed soil and damaged landscapes provided ideal conditions for colonization.
Without intervention, stiltgrass forms dense mats that crowd out native vegetation and change soil nutrient cycle properties, which can in turn affect the health and growth of native trees. In the fall, a thick layer of dead vegetation suffocates any native species below. Because it is relatively unpalatable to deer, it may lead to heavier browsing on other native vegetation. This makes early detection and proactive management critical for protecting local ecosystems.
Manual Removal Methods
Japanese stiltgrass spreads quickly, so timely removal is essential. The best time to remove it is before seed production, typically in August–early September.
Hand-Pulling: Ideal for small patches—pull plants when the soil is moist to remove roots completely.
Mowing or String-Trimming: Cut stiltgrass close to the ground before seeds form to prevent further spread.
Bag & Dispose: Seal removed plants in trash bags—do not compost, as seeds can remain viable and spread.
Preventing Future Growth
Regular Monitoring: Inspect trails, roadsides, and disturbed areas for regrowth.
Managing the Seed Bank: Prevent further spread by removing plants before they flower each season.
Limit Soil Disturbance: Avoid excessive clearing—stiltgrass thrives in disturbed environments.
Mulching: Apply 3–4 inches of mulch in affected areas to suppress regrowth.
Encourage Native Growth: Plant fast-growing native species (ferns, sedges, shade-tolerant wildflowers) to compete with stiltgrass.
Clean Equipment: Seeds cling to boots, tools, and vehicles—always clean gear after working in infested areas.
Community Action: Working Together
Coordinate removal efforts with neighbors, especially along shared roadsides and trails.
Share removal strategies at TLPOA meetings or via email to improve effectiveness.
Join the TLPOA Annual Stiltgrass Pull! Participate in a community-wide removal event in August—details to come.
For additional eradication strategies, consult the PA DCNR document. (Be mindful that TLPOA prioritizes non-toxic approaches.)
Spongy moth
At Twin Lakes, we all play a role in keeping our forests healthy. TLPOA and its affiliate organizations take a balanced, hands-on approach to managing spongy moths—focusing on monitoring, prevention, and smart intervention while keeping aerial spraying as a last resort.
We don’t tackle this alone—we consult county, state, and regional experts, including Penn State, the Pennsylvania Department of Conservation and Natural Resources (PA DCNR), and the Pike County Conservation District, to ensure our methods align with the latest scientific recommendations and best practices.
Understanding Spongy Moths
Spongy moths (Lymantria dispar) are an invasive species that can cause serious damage to trees during outbreak years. They are highly adaptable feeders who primarily target hardwood trees such as oaks, maples, and birches, but they can also feed on over 300 different species of trees and shrubs. During periods of heavy infestation, repeated defoliation can significantly injure, weaken or even kill trees. Managing their populations helps keep forests healthy and prevents unnecessary tree loss.
Spongy moth outbreaks tend to follow natural cycles, occurring approximately once a decade and lasting several years before populations drop due to disease and other environmental factors. Pennsylvania’s most recent outbreak started in 2021 and has affected forests across the region.
The life cycle of spongy moths begins in spring when eggs hatch into larvae (caterpillars) in April to May. These larvae feed on tree foliage for about six to eight weeks, passing through up to six stages called instars. After feeding, the larvae pupate and emerge as adult moths in mid to late summer. Adult moths do not feed; their sole purpose is to reproduce. Females lay egg masses in June and July, shortly after mating, and the cycle begins anew.
Our Approach
At Twin Lakes, we try to prevent spongy moth infestations before they get out of control. Our main strategies focus on population monitoring, egg mass removal, and other strategic interventions. However, if population monitoring indicates a particularly bad infestation for the coming year, aerial spraying of a biopesticide made from naturally occurring bacteria may be a last resort to effectively protect trees.
The biopesticide most commonly applied to combat spongy moths contains Bacillus thuringiensis var. kurstaki (BTk), a bacterium that, when ingested, causes starvation in caterpillars. BTk has been used in Pennsylvania since 1972 and is recommended by the Pennsylvania Department of Conservation and Natural Resources (PA DCNR). It is harmless to people, animals, and plants, but can affect other young moth and butterfly larvae. Timing of the application of BTk is critical to target spongy moth caterpillars when they are small and most affected, while minimizing exposure to species other than spongy moths.
In the past two decades, TLPOA has only used aerial spraying twice, with the latest treatment in May 2023, both times with good results.
Why Timing Matters
Each year in late summer, the TLPOA asks residents to complete a spongy moth egg mass survey of their properties. After evaluating the results of this survey, the Forest, Tree, and Plant Life Committee shares its annual assessment at the TLPOA September General Meeting. In the rare event that aerial spraying is recommended, the proposal goes to a community vote to keep the process transparent and homeowner-focused. If spraying moves forward, TLPOA will reach out to neighboring communities to gauge their interest in joining a more regional spray event as this will increase the effectiveness and reduce costs of the application. After that, the TLPOA provides educational materials to residents, offers an opt-out option for residents who choose not to participate and collects fees from all others. All of these steps have to be completed by late October/early November to be able to hire a contractor and allow for the time it takes to prepare the pesticides, apply for permits and schedule the spraying event to take place in May.
Current Community Update
For 2025, TLPOA has decided spraying is not needed based on the fall 2024 egg survey result. Please refer to the January 2025 Twin-Breeze Vol. 5 for additional details on the Spongy Moth update and recommendations on how the community can help with keeping infestations in check.
For additional information on spongy moths, please visit:
-Pike County - Spongy Moth Management Presentation September 2024
Hemlock Wooly Adelgid
The Eastern Hemlock (Tsuga canadensis) is a defining tree of Twin Lakes, shaping both its natural beauty and ecological stability. As Pennsylvania’s state tree, it plays a vital role in stabilizing forests, lake shores, riparian buffers, and watersheds, creating a distinctive landscape that supports wildlife and preserves the integrity of our environment. Unfortunately, Hemlocks are threatened by Hemlock Woolly Adelgid (Adelges tsugae), an invasive insect that weakens and eventually kills them.
Unlike spongy moth management, TLPOA does not have a community program to manage Hemlock Woolly Adelgid (HWA), as it is significantly harder to control across large forested areas. However, there are steps residents can take to help slow its spread.
Identify Hemlock Woolly Adelgid
Check trees for signs of infestation:
White, woolly egg masses at the base of needles (visible late fall–early spring).
Thinning foliage and premature needle loss.
Grayish-green needles instead of deep green.
Dieback of lower branches, progressing upward.
Learn More: Identifying HWA video
Strengthen & Maintain Hemlocks
Healthy trees are more resilient to environmental stresses. Support Hemlocks by:
Leaving natural leaf litter, branches, and organic debris to decompose and nourish the soil.
Avoiding excessive clearing of undergrowth, which provides habitat for beneficial insects, birds, and fungi.
Watering deeply during droughts, if feasible, to prevent stress.
Pruning selectively—remove dead or infested branches to slow adelgid spread, but avoid excessive thinning, which can weaken trees.
Disposing of pruning debris carefully—never leave infected branches near infested Hemlocks to prevent further spread.
Consulting a certified arborist before making significant cuts or treating declining trees.
Clean Tools to Prevent Spread
Proper sanitation prevents spreading HWA to healthy trees:
Disinfect pruning tools (shears, saws, gloves) with 10% bleach or rubbing alcohol solution after use.
Never use unclean tools on other trees.
Support Birds for Natural Pest Control
Several bird species found in Twin Lakes, including Black-capped Chickadees, Tufted Titmice, White-breasted Nuthatches, Downy and Hairy Woodpeckers, and Golden-crowned Kinglets, may help control Hemlock Woolly Adelgid populations.
Plant and maintain native shrubs to provide nesting and perching areas.
Preserve surrounding vegetation to encourage natural bird activity.
Never place birdhouses directly in trees—mount them on poles or posts near natural cover.
Future Outlook
Scientists continue to research biological control methods, including predatory beetles, fungal pathogens, and hybrid-resistant Hemlocks. While Hemlock Woolly Adelgid remains a serious threat, conservation efforts aim to slow its spread and protect remaining Hemlocks.
Learn More
spotted laternfly
The spotted lanternfly (Lycorma delicatula), native to Asia, was first detected in the United States in 2014, specifically in southeastern Pennsylvania. Since then, it has spread to, and become established in, several US states. While this pest is most damaging to grapes and tree of heaven, it feeds on a wide range of crops, ornamental plants and various hardwood trees.
The primary concern at Twin Lakes is branch dieback and potential weakening of several common trees in our local woods, such as black walnut, maple, birch, black cherry and willow. Additionally, the sticky honeydew excreted by these insects accumulates on outdoor spaces, attracts other pests and insects and promotes the growth of sooty mold fungi, which can further damage plants covered by this substance. In areas of heavy infestation, all these factors combined can seriously affect the level at which residents can enjoy their outdoor areas.
Life Stages & Identification
Egg Masses (Laid in late fall)
Gray-brown, mud-like masses found on trees, rocks, outdoor furniture, and vehicles.
Nymphs (Spring–Summer)
Black with white spots in early stages.
Red patches with white spots as they mature.
Adults (Late Summer–Early Fall)
About 1 inch long with gray forewings and striking red hindwings.
Most active from late August to early fall in Twin Lakes
Managing Spotted Lanternflies
Kill on Sight: Best Immediate Action
Smash adults & nymphs when spotted.
Scrape and destroy egg masses using a stiff tool and place them in a sealed plastic bag with rubbing alcohol or hand sanitizer.
Avoid using broad-spectrum pesticides, as they harm beneficial insects.
For more information: Penn State Lanternfly Management Guide
Diseases Common to Twin Lakes Trees and Shrubs
To Learn about other diseases that may affect trees and shrubs in our area, please click on the following links to Penn State University resources:
General PA Information
PA DCNR Invasive Pests and Diseases
Invasive Plants in Riparian Areas PLEASE NOTE: This guide mentions the use of systemic herbicides including glyphosate and triclopyr on many occasions. The Forest, Tree and Plant Life Committee does not endorse the use of chemicals as a control method as many studies suggest these herbicides can have negative effects on aquatic life, insects and wildlife.