Polk County’s Most Wanted – Insect!

Published 11:36 pm Tuesday, October 8, 2019

In a joint effort to expand the knowledge and understanding of the flora and fauna of Polk County, Conserving Carolina and botanist/ecologist David Campbell need your help in locating this month’s “Polk County’s Most Wanted—Insect,” the Sugar Maple Borer (Glycobius speciosus), a Long-horned Beetle. 

As its common name suggests, the Sugar Maple Borer, in its larval stages, feeds on Sugar Maple (Acer saccharum) trees, its only known host. Although not an abundant tree on our area, the Sugar Maple does occur in Polk County; it is fairly common in the mountains of North Carolina and can be found in the Piedmont where the bedrock is basic. Adult Sugar Maple Borers are large and robust and mimic Yellow Jackets. The adult is about 1 inch long, black, and has yellow markings. The head is bright yellow and the thorax (center section of the insect directly behind the head) has two parallel yellow bands on each side that are not joined in the middle. The wing covers on its back, or dorsal side, have five dark-yellow bands; the middle band is shaped like a “W.” The tips of the wing covers are yellow with a black spot in the center of each. 

The Sugar Maple Borer has a two-year life cycle. Beetle activity begins late in the spring. Adults are long lived, producing eggs from mid-June through August. Most eggs are laid in natural cracks or crevices in the bark, on the trunk of the tree, or near the base of the large branch; usually 30 feet up or lower.

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After hatching, larvae bore into the cambium, the area between the bark and wood, of the tree. In this area, larvae construct meandering mines, or tunnels, while they feed. By early fall the larva is about one-half inch long and overwinters in a shallow excavation in the sapwood. The second year, it resumes mining, etching a deep groove in the sapwood, longitudinally. These larval tunnels interrupt the natural flow of food and water in the tree and may cause premature foliage discoloration and eventual death to parts of the tree. With the coming of winter, the second-year larva bores a J-shaped tunnel deep into the wood. Then, before spring pupation, the larva chews a hole to the outside where it will emerge as an adult in June or July.

This insect is best recognized by the damage the larvae cause to Sugar Maple trees and this can be observed year-round. Evidence of larval activity can be seen as horizontal scars formed on the trunk of the tree and these scars may persist for many years. Often, multiple trees are attacked and scars appear on all diameters of Sugar Maple trees; however, they are most pronounced on larger trees. Until recently, this beetle was thought of as exclusively northern in distribution, however there have been recent collection in North Carolina and Alabama!

If you think that you have seen this beautiful beetle or evidence of its larvae on Sugar Maple trees, please submit a photograph to Pam Torlina at Conserving Carolina by email at pam@conservingcarolina.org, so we can document its occurrence in Polk County. 


Visit Conserving Carolina’s website, conservingcarolina.org/polk-most-wanted, for more information about “Polk County’s Most Wanted” and to download and print a “Pocket Guide” with all of the “Most Wanted” plants, animals, and habitats that you can be on the lookout for! 


Now available for purchase on Amazon or free download: “An Inventory of the Significant Natural Areas of Polk County, North Carolina,” a culmination of David Campbell’s seven years in the field documenting the rare and significant flora and fauna in Polk County. The document can be downloaded from Conserving Carolina’s website at conservingcarolina.org/polk-county-inventory.


Conserving Carolina, your local land trust, is dedicated to protecting land and water, promoting good stewardship, and creating opportunities for people to enjoy nature. Learn more and become a member at conservingcarolina.org.


Pam Torlina


The adult Sugar Maple Borer / Photo by Ronald S. Kelley


A scar left on the trunk of a Sugar Maple tree after damage by the larva of the Sugar Maple Borer / Photo by Steven Katovich