1. Introduction
  2. Types of Biological Controls
  3. What HRI is Doing
  4. What Others are Doing
  5. HWA Predator Monitoring at Home

What HRI is Doing


The Hemlock Restoration Initiative has been involved with biological control of HWA since our inception.  Today, we continue to advance biocontrol efforts across the state in the ways discussed below.  In partnership with other organizations and government agencies, the aim of our biocontrol program is to establish HWA predators across the range of hemlock forests in North Carolina, trying to cover all areas and fill in gaps where predators might not have spread yet, and integrating chemical and biological control as pieces of a larger integrated pest management strategy.  One result of this program is to alleviate the need for individual landowners to attempt to source or purchase beetles on their own, which can be difficult and expensive.

Our biological control program seeks to establish a predator-prey balance by introducing natural HWA predators to bring the HWA population down to levels that our native hemlocks can tolerate. This would allow us to reduce our dependence on chemicals as the primary means of protecting hemlocks from HWA.

Releases and Insectaries

This large hedge is one example of a possible insectary site.

With the support of county funding and partnering non-profits, the HRI has established local insectaries where predator beetles can breed and become established, to later be collected and re-distributed. Good insectaries are both well-infested with HWA but also in relatively good health, and they have easy access to live branches so beetles can be collected in the future.  These insectaries will increase the number of HWA predators present in southern Appalachian forests and reduce dependence on resource intensive procurement methods, like wild collection or lab production.

BRRCD4-Aug- colorLearn about the “Beetles Save Needles” program and community trainings hosted by the Blue Ridge Resource Conservation and Development Council, an HRI partner and award recipient here.  In February 2016 the NC HWA Bio-control Forum was held in Montreat, NC. Videos of the presentations are available upon request.

buncombe-countyIn 2015, Buncombe County decided to take a lead role in preparing our region to transition away from a reliance on chemical pesticides as the primary strategy for protecting our native hemlock trees from HWA. The County’s strategy is to build up local populations of Laricobius beetles, a natural predator of HWA, contributing to a gradual reduction of local HWA populations down to a level hemlocks can tolerate. This integrated biological control program prioritizes old-growth Carolina and eastern hemlock stands across the county, in addition to identifying sites that might make good insectaries. Partners include the City of Asheville, Montreat, NC Wildlife Resources Commission, local colleges, land conservancies and other NGOs.

Between 2015-2018, over 13,000 beetles were released onto nine Carolina hemlock stands, nine eastern hemlock stands and two insectary hedges, as a result of the “Bringing Beetles to Buncombe” program. Seasonal monitoring of Laricobius populations shows promising signs of establishment. Thank you to the foresight of county commissioners for taking action on this important issue by bringing the beetles to the needles.

NCDA&CS Beneficial Insect Lab in Cary, NC

HRI also works closely with the NCDA&CS Plant Industry Division’s Beneficial Insect Lab to establish colonies of Laricobius nigrinus and Laricobius osakensis and they along with the Lindsay Young Beneficial Insects Laboratory at the University of Tennessee have helped us procure additional beetles for strategic release on promising biocontrol sites.


HRI monitors for Laricobius beetles throughout the active season (fall through spring).  HRI staff visit previous release sites as well as new areas to look for dispersal. To date, HRI has found Laricobius beetles persisting in release sites and even spreading to new areas. We are hopeful about this development and plan to continue looking in more areas for evidence of natural dispersal by the beetles.

You can help with beetle monitoring in two ways. One is to join HRI for a volunteer beetle monitoring day.  Fill out our Volunteer Sign Up Form to register. Another way is to look for beetles on your own hemlock trees.  See our HWA Predator Home Monitoring page for more information.

Information Sharing

HRI also shares information about our biocontrol activities with our partners, the scientific community, and the public.  We submit collected data on releases to a central database managed by Virginia Tech.  We also attend periodic meetings with partners from other states to share our progress and hear about their biocontrol activities.  Finally, we keep our local partners up-to-date on the latest in biocontrol of HWA, and share that information with the public through educational and training programs.

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