US Forest Service Research & Development
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  • US Forest Service Research & Development
  • 1400 Independence Ave., SW
  • Washington, D.C. 20250-0003
  • 800-832-1355
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Nathan P. Havill

Research Entomologist
51 Mill Pond Rd.
United States

Phone: 203-230-4320
Contact Nathan P. Havill

Current Research

With expertise in the ecology and evolution of multi-trophic interactions, I work to provide information about invasive pests, their natural enemies, and the impacted trees. Understanding the interactions among these trophic levels is critical to making sound management decisions to reduce the impact of invasive pests. Facets of my research objectives include investigating: 1) systematics and population genetics of invasive pests, especially hemlock woolly adelgid, balsam woolly adelgid, gypsy moth, and winter moth; 2) systematics and population genetics of predators and parasitoids being evaluated as biological control agents of invasive species, especially of hemlock woolly adelgid and emerald ash borer; and 3) systematics and biogeography of North American tree species and their relatives worldwide.

My goal is to help reconstruct the evolutionary history of multiple trophic levels of a pest system to guide management and mitigate the impact of invasive insect pests on forested ecosystems of the northeastern United States. I am especially concerned with research related to classical biological control to develop practical, cost effective tools used to evaluate the safety and efficacy of predators or parasites introduced as biological control agents.

Why This Research is Important

The exotic invasive pests that are the subject of this research originated in either Asia or Europe. Invasive insects in North America are not often pests in their region of origin due to resistant tree species and natural enemies that co-evolved with the pest over millions of years. The insect becomes a pest following introduction outside its native ranges when these bottom-up and/or top-down regulating factors are no long effective. The hemlock woolly adelgid, Adelges tsugae (Adelgidae), originated in Japan and causes the death and decline of eastern North American hemlock trees in 17 eastern states. The balsam woolly adelgid, Adelges piceae (Adelgidae), originated in Europe and has been killing fir trees throughout North America for over 100 years. The gypsy moth, Lymantria dispar (Lymantriidae), also was also introduced from Europe over 100 years ago. It is controlled to some extent by a pathogenic fungus in areas where it is well established, so management in the U. S. currently focuses on slowing its spread and on preventing invasion by more virulent strains from Asia. The winter moth, Operophtera brumata (Geometridae), is also from Europe and defoliates a broad range of tree species, including oaks and birches in southern New England, and is hybridizing with the native Bruce spanworm, O. bruceata. Finally, the emerald ash borer, Agrilus planipennis (Buprestidae) originated in Asia, was first discovered in the U.S. in Michigan in 2002, and has killed tens of millions of ash trees in at least 15 eastern states. Together, these pest species represent a diverse group of insects with very different feeding strategies, life cycles, host ranges, and natural enemy complexes.


  • Yale University, Ph.D. Ecology & Evolutionary Biology 2006
  • Yale University, M.S. Ecology & Evolutionary Biology 2003
  • University of Wisconsin, Madison, M.S. Entomology 1998
  • College of William and Mary, B.S. Biology 1996

Professional Organizations

  • Society for the Study of Evolution, Member (2012 - Current)
  • Connecticut Entomological Society, Member (2001 - Current)
  • Entomological Society of America, Member (1996 - Current)

Featured Publications & Products


Research Highlights


A Tree Species’ Evolutionary History Predicts Impact of Invasive Pests

Research by Northern Research Station scientists and their partners presents the first evidence supporting a long-held hypothesis that a tree’ ...


First Release of a New Biological Control of Hemlock Woolly Adelgid

Forest Service scientists and their research partners tested and released two species of silver flies from the western United States for biologi ...


Non-native Insect Hybridization Provides Opportunity for Research

A recent outbreak in New England of the non-native winter moth from Europe provides an unprecedented opportunity to examine the effects of hybri ...


Silver flies show promise as potential biological controls of hemlock woolly adelgid

Forest Service science is identifying potential biological control of hemlock wooly adelgid, an invasive insect that is devastating hemlock tree ...


Last updated on : 09/15/2021