What are Biocontrols?

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

Overveiw of SLELO PRISM Biocontrol Program

Emerald Ash Borer (EAB) Biocontrol:

We are currently releasing three species of parasitoid wasps (Spathius galinae, Tetrastichus planipennisi, and Oobius agrili) that target EAB at Rice Creek Field Station (SUNY Oswego).  This is the 2nd year of the USDA’s two year release program.  Last year, we released a total of 5689 Wasps in 8 releases. So far, this year, we have completed four releases for a total of 2914.  We still have four more releases and expect a similar total as last year.


Spathius galinae a biocontrol for Emerald Ash Borer. © SLELO PRISM/TNC

Swallow-wort Biocontrol:

We have four cages set up for Hypena opulenta moths- the biocontrol for swallow-wort; two of these are at Wehle State Park, and two of these are at Grenadier Island.  40 Pupae were placed in each cage on June 6.  Unfortunately, only 1 cage had adults emerge.  We are not alone in this lack of emergence.  Other Hypena Biocontrol Sites also had no emergence.  Pupae from different sites were brought to SUNY ESF, where Dylan Parry, an entomologist involved in the biocontrol program is examining them, to determine cause of non-emergence.  We will be getting a new shipment of Hypena Moth (larvae, pupae, adult) on July 25.  Hopefully, these will do much better than the first release.  A June Trail Survey for evidence of overwintering was conducted by SLELO PRISM and OPRHP and did not find evidence of presence.  All trails are being surveyed again in July and August.  Residents of Grenadier Island have received training on how to identify Hypena and evidence of their presence.  They are actively searching for their properties when traveling around the island.  So far, no reports of Hypena presence.


Preparing to release Hypena opulenta, biocontrol for swallow-wort. © SLELO PRISM/TNC

Hemlock Woolly Adelgid (HWA) Biocontrol:

In May, OPRHP with assistance from SLELO PRISM released 1,347 Silver Flies at Selkirk Shores State Park.  There are plans to release Laricobius Beetles at Independence Park this Fall and hopefully, we will be able to release silver flies next spring at Independence Park. There are three species of insects that are used for HWA.  These are a beetle (laricobius nigrinus) and silver flies (leucopis argenticollis) and (Leucotaraxis piniperda).  The biocontrol insects are provided by the New York State Hemlock Initiative. 


Leucotaraxis piniperda a biocontrol for Hemlock Woolly Adelgid. © SLELO PRISM/TNC

Swallow-wort Biocontrol in SLELO

Native to Ukraine, swallowwort was likely introduced to North America as an ornamental plant, soon
spreading to several northeastern states. The plant creates extremely dense monocultures spreading over
acres upon acres of otherwise biologically diverse natural systems. The biological control, Hypena opulenta, is
also from the Ukraine and feeds exclusively on swallowwort.

Partnering with the NYS Invasive Species Research Institute, the Thousand Islands Land Trust, SUNY ESF,
University of Rhode Island, the USDA Agricultural Research Service and local volunteers, our SLELO PRISM
assisted with caged releases of Hypena opulenta at four sites within the Eastern Lake Ontario and St. Lawrence
Region. This important work will help to restore Priority Conservation Areas (PCA’s) to their natural ecological

Identifying Hypena opulenta

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 from the egg as a larva.  This larva goes through five stages or instars. The last molt occurs at the end of the 5th instar and transforms the larva into a pupa.  Metamorphosis occurs inside the pupa and results in the emergence of an adult winged moth. 

Adult Hypena opulenta lay between 600 to 400 eggs during an average 2-3 week lifespan.  Two generations may occur in the same year. The larvae feed exclusively on pale and black swallowwort and this was the reason that they were selected as a biocontrol.

Photos from the field

Hypena opulenta pupae being readied for release.

Pupae remain in the release bucket until they mature into egg-laying adults inside the screened cage. 

One of four 6’x6’x6’ research cages.

Adult Hypena opulenta emerged from pupae. 

Cage Monitoring Stats & Reports

2022-23 Field Season Overviews

2021 Field Season Overview

2020 Field Season Overview

The Eastern Lake Ontario Swallow-wort Collaborative (ELOSC), is a platform for sharing the most up-to-date research and best management practices to inform stakeholders about the prevention and management of invasive swallow-wort.

Learn More About Swallow-wort

Biocontrol Webinar Recordings

Hosted by the Eastern Lake Ontario Swallow-wort Collaborative on March 23rd, 2022. This webinar showcased swallow-wort biocontrol research that is currently underway in New York state and beyond.
Researchers from New York, Rhode Island, and Michigan provided an overview of their research, along with the results of an ongoing Hypena opulenta cage monitoring project that SLELO PRISM participates in.
  • Dr. Lisa Tewksbury- University of Rhode Island Biocontrol Lab
  • Dr. Marianna Szucs- Michigan State University
  • Robert Smith-SLELO PRISM
  • Dr. Dylan Parry- SUNY ESF

Rob Williams                              rwilliams@tnc.org                     Program Director

Megan Pistolese megan.pistolese@tnc.org
Outreach and Education

Brittney Rogers brittney.rogers@tnc.org 
Aquatic Invasive Species

Robert Smith       robert.l.smith@tnc.org 
Terrestrial Invasive Species

Zachary Simek    zachary.simek@TNC.ORG     Conservation and GIS Analyst

During this time the best way to contact our team is via email.