Column: Be on the lookout for bad bugs in the High Country

In the 1950s this insect was discovered in Virginia and has slowly spread throughout the Eastern U.S. They have an interesting life cycle. Females (no males are needed to make new adelgids!) lay eggs that hatch into wingless “crawlers”, which then move about the tree feeding on branches where they eventually produce their white covering. Because females produce many eggs, the adelgid population can be enormous on an individual tree. To make matters worse, there is more than one generation produced per year.

Chemicals can be used to protect individual trees, but this is not a practical or indeed safe solution for large numbers of trees. Though hemlocks possess few natural defenses against the woolly adelgid, there is some good news. Researchers are finding success rearing and releasing in very large numbers small beetles that eat the adelgid, reducing their populations and in some cases resulting in tree recovery. If successful, over the long term the beetle-releasing biological control strategy could provide a way for our hemlocks to survive and thrive in the years to come.

The emerald ash borer, Agrilus planipennis, gets its name from the metallic green adult beetle. Though handsome in appearance, this bugs effects on our native ash trees is devastating. A native of Asia, this wood-boring insect first appeared in the upper midwestern US but has since rapidly spread. Unlike the sap-sucking hemlock woolly adelgid, the emerald ash borer feeds under the tree bark. Adults are found in spring feeding on the ash leaves and after mating the female lays eggs. The young (larvae) and bore into the bark, where their feeding cuts off the food supply throughout the tree, eventually resulting in tree death. Distinctive “galleries” are carved into the wood by the munching insects. Larvae overwinter in the tree and in spring produce a pupa that develops into an adult. The metallic beetles bore out of the tree leaving a visible hole, begin to eat, and the cycle continues.

Attacked trees may succumb in a few years (or sooner), leaving behind the tell-tale galleries in the wood as the bark peals away. Ash trees possess few natural defenses against the emerald ash borer, although researchers are exploring releasing small parasitic wasps that kill it. You may notice the next time you’re camping warning signs about not taking firewood from where you are into other areas. That’s because the emerald ash borer can easily be transported to places it is not found through the wood. It is especially important to take these warnings seriously to prevent further spread of this damaging insect.

Though the hemlock woolly adelgid, and more recently the emerald ash borer, have become established unwelcome invasive insects, we need to be diligently watching for other concerning invasive bugs that may soon find our area home. This is especially true for the plant-sucking spotted lanternfly, Lycorma delicatula. Also a native of Asia, this highly damaging bug threatens agricultural plants (including fruit trees) and especially grapes. Originally found in Pennsylvania, and established now in parts of nearby southern Virginia, the spotted lanternfly’s incidence in North Carolina just to our east is currently limited but likely to increase in the future. Fortunately reports of this serious pest in the High Country are not known at this time.

The adult lanternfly has black spots on grayish wings and is sometimes confused with some moths; you have to look closely to properly identify it. The movement of this insect is not so much from adults flying but eggs being carried on vehicles, wood, transported structures, etc. Carefully inspecting belongings before leaving areas where the spotted lanternfly exists is important. Good information on identifying this insect, and for reporting sightings, may be found at content.ces.ncsu.edu/spotted-lanternfly and www.ncagr.gov/plantindustry/plant/entomology/documents/SpottedLanternflyPestWatch.pdf.

Though unwelcome, invasive insects are becoming part of our local insect communities through unfortunate introductions, and by the great capacity for bugs to move around. When spring arrives watching out for the bugs discussed in this article, and reporting incidents of new invaders, will assist in helping state and local agencies develop good policies to hopefully control their impacts. Sources and additional information on the insects in this article may be found using the searchable website https://content.ces.ncsu.edu

Dr. Ray Williams is a native of Asheville, and Professor Emeritus in the Department of Biology at Appalachian State University, where he taught for 25 years. What he tried to instill in his students is the fascinating lives of insects, which he continues to research and write about in retirement. He lives in Boone with his wife, Beverly, and has two children in college. He will write a semi-regular column on local insects in the area. For questions or comments, email bugmanofboone@gmail.com