ST. LAWRENCE EASTERN LAKE ONTARIO PARTNERSHIP FOR REGIONAL INVASIVE SPECIES MANAGEMENT
The terms biocontrol or biocontrols refer to using one species to control another. One of the biggest reasons that invasive species are able to have such an impact on ecosystems is that they often lack natural predators in the areas they are introduced to. Biocontrols can be used to control invasive species. This involves bringing natural predators from areas where the invasive species is native and releasing them in the ecosystems in which you want to control the invasive.
Biocontrols can offer a long-term solution for the suppression of many widespread invasive species. However, biocontrols are not a “solve-all” solution. For a biocontrol to be approved for release it undergoes intensive research and trials to ensure that applied biocontrols will only impact the target species. This process can take a long time to complete. In addition, there aren’t approved biocontrols available for every invasive species, and it can take multiple years for released biocontrol populations to become established enough to make a difference. In New York, biocontrols have been successfully used to suppress purple loosestrife, and there are approved agents being released in the state to control hemlock woolly adelgid, emerald ash borer, and swallow-wort. You can learn more about biocontrol research being done in NYS at the New York State Invasive Species Research Institute, as well as in this USDA Field Guide.
Spotted Knapweed Biocontrol:
At Deer Creek Marsh Wildlife Management Area, SLELO PRISM has released two beneficial insects to help manage invasive spotted knapweed (Centaurea stoebe), the spotted knapweed flower weevil (Larinus spp.), and the spotted knapweed root weevil (Cyphocleonus achates). A total of 800 individuals (400 of each species) were released at the site.
These weevils were carefully chosen for their ability to target different parts of spotted knapweed flowers and roots—working together to gradually reduce its impact.
Spotted knapweed threatens the dunes of eastern Lake Ontario by crowding out native plants, degrading wildlife habitat, and increasing erosion. Its spread can lead to monocultures and disrupt natural dune succession.
This biocontrol release supports long-term ecosystem health and helps protect the biodiversity and resilience of our coastal landscapes.
Resources:
Emerald Ash Borer (EAB) Biocontrol:
In the summer of 2022 and 2023, we released three species of parasitoid wasps (Spathius galinae, Tetrastichus planipennisi, and Oobius agrili) at the SUNY Oswego Rice Creek Field Station. These wasps are biocontrol agents that target the emerald ash borer.
With the help of dedicated volunteers, we monitored the site for the presence of these wasps in the summer of 2024 and 2025
To detect if populations of the parasitoid wasps have become established, we set up pan traps and conducted monitoring surveys from June to September in 2024 and 2025.
Specimens were sent to the USDA for further identification. In 2024, all three parasitoid wasps were confirmed present in our samples. In 2025, only two out of the three parasitoid wasps (Spathius galinae and Tetrastichus planipennis) were confirmed. We’re awaiting a response from USDA to determine if all three parasitoid wasps (Spathius galinae, Tetrastichus planipennisi, and Oobius agrili) are confirmed to be successfully established at the site.
Hemlock Woolly Adelgid (HWA) Biocontrol:
1,969 Leucotaraxis piniperda silver flies were released at Selkirk Shores SP on May 23rd. 1,998 Leucotaraxis piniperda silver flies were released at Mexico Point SP on April 16th. The biocontrol insects are provided by the New York State Hemlock Initiative.
Native to Ukraine, pale swallow‑wort was likely brought to North America as an ornamental and quickly spread across the Northeast, forming dense monocultures that displace diverse native plant communities.
The biocontrol moth Hypena opulenta, also from Ukraine and specialized to feed on pale swallow‑wort, was released at four sites between 2018 and 2024 through a partnership involving the NYS Invasive Species Research Institute, the Thousand Islands Land Trust, SUNY ESF, the University of Rhode Island, the USDA Agricultural Research Service, local volunteers, and SLELO PRISM.
From 2020 to 2025, establishment surveys at Wehle State Park and Grenadier Island found no H. opulenta moths or signs of their activity. Based on these results and earlier years of monitoring, future releases and surveys for this biocontrol will be discontinued. Chemical and manual/mechanical control efforts will continue until another approved biocontrol becomes available.
SLELO PRISM Swallowwort Biocontrol Reports:
Hypena opulenta adults are one cm long with a wingspan of about 3cm. They have dull, light brown forewings with a dark band in the middle and hindwings that are pale orange.
The larvae start out white, but later become green with black spots and a yellow head.
The life cycle of Hypena starts with the emergence of the egg as a larva. This larva goes through five stages or instars. The last molt occurs at the end of the 5th instar in which the larva transforms into pupae. Metamorphosis occurs inside the pupa and results in the emergence of an adult-winged moth.
Adult Hypena opulenta lay between 400 to 600 eggs during an average 2-3 week lifespan. Two generations may occur in the same year. H. opulenta larvae feed exclusively on pale and black swallowwort making them a prime candidate for biocontrol.
