An Unwelcome Visitor Comes to ACLT
- ACLT American Chestnut Land Trust
- 4 hours ago
- 3 min read
By Addy Dunbar, Double Oak Farm Manager
2025-2026 Climate Corps and Maryland Corps Member
A new and not-so-welcome visitor is coming to Southern Maryland, and we’ve got our first few
arrivals at ACLT. The spotted lanternfly (SLF), an invasive insect species native to China, Vietnam, and India, has been in the US since 2014, when it was first identified in Pennsylvania. Since its arrival, the species has spread across much of the Mid-Atlantic, reaching Calvert County for the first time in 2022 and ACLT this fall. An ACLT staff member spotted our first SLF on the Gravatt East property on October 24th, and a few more on the Commodore property the following day.
The true scale of the invasion that ACLT faces may not be clear until the Spring. The spotted lanternfly has a year-long lifecycle, with egg masses overwintering to emerge in May or June. The nymphs molt four times before reaching adulthood between July and September. Thus, in the summer of 2026, ACLT will see its second generation of adult SLF, and without mitigation, each new generation could be 60 times larger. After mating in the fall, female SLF lay one or two egg masses of 30-60 eggs, which look like cracked mortar when dry. In their native environment, this volume of eggs is necessary for the survival and growth of the species, as nymphs face predation and other limiting conditions. In Southern Maryland, however, it may mean exponential population growth during the seasons it takes for the area’s predators to catch on.
SLF can have a far-reaching impact on the ecosystems that it enters. The insect population feeds indiscriminately on over 70 different species of plants. SLF does have a preference for the invasive tree-of-heaven, unfortunately present at ACLT, but can and will persist without this host as well. The insect’s feeding alone rarely kills its host, but when combined with other stressors, it has this potential. SLF use piercing-sucking mouthparts to extract sap from young leaves and stems, and the insects excrete a sugary liquid called honeydew, which can proliferate fungal infections and attract other insects to the tree on which it feeds. The insects are known to weaken new growth and wound tree bark, weakening their hosts and leaving them vulnerable to other threats.
At ACLT, the arrival of SLF requires a new management strategy. We expect the insects to most heavily affect tree of heaven trees on ACLT property, as well as grape vines, maples, and black walnuts. The SLF’s preference for fruit trees and other food crops may also mean that they will thrive on ACLT’s farm and in the food forest. Those who frequent the trails can help our containment efforts by squishing any SLF they see. On a larger scale, ACLT may consider management strategies such as removing egg masses in the fall and winter, spraying adult SLF with vinegar or neem oil, or treating tree of heaven trees with systemic herbicides harmful to the insects. [1] [2] The farm may consider netting trees and planting more native milkweed, which early research indicates may kill 60-80% of SLF that feed on it. A grapevine removal project has already been carried out to reduce SLF draw to the food forest.
Spotted lanternflies are unfortunately likely to stick around, at ACLT and elsewhere. ACLT’s Land Manager, Autumn, says this highlights the importance of prevention in the invasive species realm, fighting against invasions before they begin. Going forward, the land management team will learn to manage this new threat, focusing on where it will have the greatest impact at ACLT. As with many invasive mitigation projects, we will rely on our community’s support and attention to protect the land for generations to come.
Sources:
ACLT Invasive Species Control Plan 2024-2028
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