Scientists & Staff

Leah Bauer, Research Entomologist

Leah Bauer

Research Entomologist, Emerit
3101 Discovery Dr., Ste. F
Lansing, MI, 48910
Phone: 517-884-8059

Contact Leah Bauer

Current Research

My research has focused on key mortality factors that regulate populations of the emerald ash borer (EAB) [Agrilus planipennis (Coleoptera: Buprestidae)] in North America, where this invasive beetle is killing native ash (Fraxinus) trees, and in its native range in Asia where it is considered only a minor ash pest. A better understanding of EAB population dynamics may facilitate the development of safe, long-term, and sustainable management strategies to better protect ash from EAB in North America. Biological control is the generally accepted method for managing invasive pests, mainly insects and weeds, in environmentally sensitive ecosystems such as forests. USDA began an EAB biocontrol program in 2007, with the approval for release of three parasitoid species from China [Tetrastichus planipennisi (Eulophidae), Oobius agrili (Encyrtidae), Spathius agrili (Braconidae)] in the U.S.  A fourth species from Russian Far East [Spathius galinae (Braconidae)], was approved for release in 2015. These four parasitoid species are currently being reared and shipped by USDA APHIS for release in the U.S. by researchers, forest managers, and landowners. Research continues on the establishment and prevalence of native and introduced EAB parasitoids, as well as the impacts of biocontrol on EAB population densities, ash health, and forest recovery in the aftermath of EAB. 

Research Interests

My collaborative research continues at long-term study sites in Michigan where we are evaluating parasitoid establishment, spread, impacts on EAB population dynamics, and impacts on ash regeneration and survival.

Why This Research is Important

Emerald ash borer (EAB), an invasive beetle from Asia is spreading in North America, causing widespread mortality of native ash (Fraxinus) trees. EAB was first discovered in southeast Michigan in 2002 and likely arrived during the 1990s in EAB-infested solid-wood packaging materials used for international trade with Asia. Despite early efforts by regulatory agencies to eradicate EAB, infestations are known in 35 states, the District of Columbia, and four Canadian provinces as of August 2018. The ecological impacts of the EAB invasion are rapidly changing the biodiversity, species composition, hydrologic processes, and nutrient and carbon cycles in our forests. The survival of ash species native to North America may require a combination of both biocontrol and the discovery or development or EAB-resistant ash genotypes.


  • University of Kentucky, Ph.D. Entomology, 1987
  • University of Maine, M.S. Entomology, 1977
  • University of Michigan, B.S. Natural Resources, 1974

Professional Organizations

  • Entomological Society of America
  • Society for Invertebrate Pathology (SIP)
  • International Organization for Biological Control
  • Michigan Entomological Society

Featured Publications & Products

Publications & Products

Other Publications

National Research Highlights

Biocontrol of the Emerald Ash Borer pest improves outlook for ash trees in North America

Year: 2017

The invasion of forests by the emerald ash borer (EAB) has resulted in the death of hundreds of millions of ash trees throughout much of the U.S. Forest Service researchers are studying how effective biocontrol methods are in managing EAB populations in Michigan forests.

An introduced natural enemy of EAB emerging from the trunk of a young ash tree regenerating at Michigan study site. Leah Bauer, U.S. Department of Agriculture Forest Service.

Emerald Ash Borer Biocontrol Benefits the Health of Young Ash Trees

Year: 2016

Forest Service research results from a multi-year study of ash trees in Michigan forests found that an introduced natural enemy of the emerald ash borer (EAB) contributed to the health and growth of young ash trees and could potentially lead to the repopulating forests decimated by EAB.

The brood of Tetrastichus adults emerging from an Emerald Ash Borer gallery in the field last fall, when dissecting an ash tree. USDA Forest Service

Guidelines for Release and Recovery of Emerald Ash Borer Biocontrol Agents

Year: 2015

Biological control is a sustainable and long-term management tool for invasive species and is now being used to control the emerald ash borer (EAB) in North America. Detailed information and instructions are available online to assist land manager participation in the U.S. Department of Agriculture’s EAB Biocontrol Program. Consequently, release of EAB biocontrol agents is ongoing in states, tribal lands, and provinces infested with EAB.

Debarking of some declining hybrid poplars revealed numerous A. fleischeri larvae and their extensive feeding galleries under the bark. Leah S. Bauer, USDA Forest Service

Mitigation of Invasive and High-Risk Wood-Boring Insects in China

Year: 2014

The number of accidental introductions of wood boring insect pests to U.S. forests from Asia has escalated dramatically during the last two decades due to increasing global trade and the use of solid-wood packaging materials. The high ecological and economic costs of these destructive tree pests, including the emerald ash borer and Asian longhorned beetle, highlight the importance of proactive research to predict, prevent, and respond to introductions of these and similar invasive woodborers.

An emerald ash borer larva feeding under the bark of an ash tree. Leah Bauer, USDA Forest Service

A suite of Introduced and Native Enemies Reduces Populations of the Emerald Ash Borer

Year: 2014

Originally from Asia, the emerald ash borer (EAB) is an invasive wood-boring beetle that attacks and kills ash trees in the United States. The long-term and sustainable management of this destructive pest involves the release of specialized insect natural enemies from Asia into our EAB-infested forests. At study sites in Michigan forests, Forest Service scientists and their research partners have found a suite of introduced and native natural enemies working in tandem to reduce populations of emerald ash borer.

Tetrastichus planipennisi, a larval parasitoid of emerald ash borer (EAB), drilling into the tree trunk to lay eggs in an EAB larva. Leah Bauer, USDA Forest Service

Natural Enemies of Emerald Ash Borer are Fighting the Good Fight in North America

Year: 2013

The emerald ash borer (EAB) continues to sweep across the North American landscape, leaving dead and dying ash trees in its wake. To reduce populations of this tree-killing beetle, Forest Service research entomologists have been releasing specific natural enemies from Asia into EAB-infested forests of North America. These natural enemies are tiny beneficial insects that eat EAB eggs and larvae. The scientists found these natural enemies have established and spread to new areas during the last five years, working to help our forests recover from the EAB invasion.

Oobius female depositing eggs inside an ash tree which may infect emerald ash borer larvae. Forest Service

Emerald Ash Borer Natural Enemies Becoming Established in the United States

Year: 2012

Optimism increasing for long-term management of the emerald ash borer

Last modified: Wednesday, July 31, 2019