Ambrosia Beetles

Ambrosia Beetles are Attacking Fig and Other Trees

This spring, Georgia seems to be experiencing a bumper year for a pest known as the ambrosia beetle. This beetle can attack over 100 types of trees and woody shrubs, and most infestations result in the death of the affected trees. The damage caused by these beetles is very apparent when the injury is fresh. When the beetle bores into the wood, it leaves behind a tube of sawdust sticking out of the trunk resembling a toothpick. These usually stick around for a few days before falling off unless rain knocks them off.

How the beetles attack

Ambrosia beetles typically attack diseased or weak trees, selecting them based of their emission of ethanol. Trees that are stressed, produce more ethanol than healthy trees and this attracts the beetles. Once a tree is selected by the beetle, it will bore into the wood and lay up to 6 eggs in the tree. The boring of the beetle produces the tell-tale sawdust plugs. Ambrosia beetles also inoculate the tree with a fungus that grows while the eggs incubate and serves as the food source for the newly hatched larva. These larvae will pupate and emerge from the tree as a beetle, ready to find another tree to bore into. Ambrosia beetles can have several life cycles per year, making early detection and intervention important to controlling this pest.

What if I see signs of damage on my trees?

If you see the signs of damage from the ambrosia beetle, the options are fairly limited and will vary slightly depending on the type of tree or shrub that is infested. If there are only a couple holes, the tree may recover with treatment, but if there are more than a few holes, more drastic measures are required to prevent spreading. The general management practice if extensive ambrosia damage is found, is the removal and burning of infected material. If the plant is more shrub-like with multiple trunks, like figs, only the damaged trunks need to be removed. Figs, along with some vigorously growing bushes or trees can regrow from their stump.

What can I do?

While the ambrosia beetle can infest a wide variety of trees and shrubs, I have seen lots of reports this year on fig trees and Japanese maples being attacked throughout Georgia. While we don’t have many great options on controlling these beetles, early detection and removal of infected plant materials is the best thing that can be done to reduce future damage by the ambrosia beetle. We are always here to help at the Banks County Extension office.