Authored by: Dr. Elizabeth McCarty Cassandra Waldrop Fall brings cooler temperatures and changing leaves, but it doesn’t always put an end to tree insect activity. Some pests remain active well into the season and can leave visible damage in branches and crowns, especially as foliage begins to thin. Two late-season insects to watch for are twig girdlers and deodar weevils. Twig girdlers Photo credit: Eugenio Nearns, Oncid ID, USDA APHIS PPQ, Bugwood.org Twig girdlers (Oncideres cingulata) are native longhorned beetles that damage smaller branches on many hardwood tree species. These beetles are about ¾ inch long and grayish-brown and can blend in with tree bark, often going unnoticed. Often, twig girdlers catch our attention when dead branch tips are still on trees or scattered on the ground below the trees. Hosts include hickory, elm, pecan, persimmon, and many other hardwoods. Photo credit: Lacy L. Hyche, Auburn University, Bugwood.org Adult females will create a notch that encircles the twig, which will ultimately kill the branch tip. She will lay eggs under the twig bark. The beetle larvae will hatch and then feed within the woody portions of dead twigs until next summer, with new adults emerging in late-summer to early-fall. Twig girdlers cause aesthetic damage to healthy trees, but they will recover. However, to reduce twig borer damage in future years, remove and destroy the dead and dying branches so that the next generation does not successfully develop. Deodar weevils (This is a shortened version of a 2021 newsletter article) Photo credit: Elizabeth McCarty, University of Georgia Photo credit: Elizabeth McCarty, University of Georgia Deodar weevils (Pissodes nemorensis) are a native wintertime pest of pine trees. They are a small (about ¼ inch) reddish brown beetle with a small head and a long snout. All species of yellow pine in the southeast are susceptible to deodar weevil attack. Unlike most forest pests that become inactive as the temperature cools, deodar weevils become active in fall. Females lay one to five eggs in small holes in the bark of a pine tree. The grublike larvae will feed on the inner bark of the tree. Larvae can grow to about ½ inch long and then will create a ‘chip cocoon’ in preparation for pupating, which is a non-feeding/immobile stage of development. Once the adult emerges in early to late-spring, they will become inactive under the tree’s bark during summer. Signs of deodar weevil infestation include browning crowns, dying branches, and bark sloughing off the trunk. Deodar weevils generally attack unhealthy trees. The best way to avoid a deodar weevil infestation is to maintain good tree stand health, meaning that if stands are properly managed they will likely face little threat from this wintertime pest.
