How much do you know about the balsam and hemlock woolly adelgids? Here are some interesting facts about hemlocks, Fraser firs and the insects that attack them.

  • Since all HWA are female, they reproduce asexually twice a year, which causes adelgid populations to increase dramatically.  One individual can lay up to 300 eggs yielding up to 90,000 new adelgids in one year.
  • Another adelgid pest, the balsam woolly adelgid (BWA), is currently threatening Fraser fir, a species native to the southeastern United States.
  • Hemlocks are long-lived, late-succession trees whose role in cooling headwater stream areas has led to their classification as a ‘foundation species’ (Ellison et al. 2005)
  • Fraser fir is a high elevation species that occupies many of the highest peaks of the southern Appalachians in the states of North Carolina, Tennessee, and Virginia.  The species occurs naturally at elevations from 1350 m to the highest peaks (2037 m at Mt. Mitchell).  At the lower elevations Fraser fir is found in mixed stands with red spruce, but at the highest elevations Fraser fir predominates
  • North Carolina’s Fraser fir is the state’s best-selling Christmas tree.  In the wild, BWA only kill mature Fraser fir, while in nursery settings they attack both young and old trees.
  • The NC Christmas tree industry is the second largest in the country.  There are 50 million Fraser fir Christmas trees growing on over 25,000 acres in NC, providing well over $100 million to the Christmas tree industry (NCCTA 2007).
  • North Carolina is third in the nation for the number of nursery growers (707) and second for area under nursery production (48,454 acres).  Farm income from nursery crops is an important part of the economy in rural counties across the state.
  • Nursery crop income is in severe decline: sales have declined 30% to 40% for many growers with 40% – 50% layoffs of employees.
  • The total economic impact of the NC Green Industry in 2005 was $8.6 billion.
  • In 2008, ornamental plants were valued at $777 million, which makes them the most valuable crop in NC and account for nearly a third of total crop value.
  • The Development of genetically resistant trees has great potential through two lines of research: 1) breeding for resistance, and 2) understanding the biological basis for resistance.
  • The U.S. Department of Agriculture (USDA) has created hemlock hybrids that are tolerant of HWA.  Scientists have crossed native U.S. hemlocks with germplasm, (collected in Asia), of hemlocks that have shown tolerance to the insect.  This has led to the development of 140 hemlock hybrids, 108 of which are suitable for testing.
  • The use of genetically resistant firs and hemlocks would be a relatively inexpensive solution to this difficult pests problem, in minimizing adverse effects from the pest and related management strategies.
  • Chemical insecticides are currently the only semi-effective means for controlling this pest and treatments exceed $1.5 million per year (Potter et al. 2005).