Twig girdlers eat through tree limbs before storms can knock them down

During the past month, we have had several storms knock down some trees and many limbs. Most of these limbs had jagged edges.

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However, there were some limbs that looked like they had been cut. I noticed a number of these limbs in yards and on the roadside before these storms.

Judging by the number of calls, a lot of you noticed them as well. These limbs were damaged by an insect called a twig girdler.

The twig girdler, Oncideres dingulata , is a wood-boring insect. Most wood-boring insects damage trees while in the larva stage. The twig girdler is different because it damages the tree as an adult.

The damage is done by the female twig girdler. The adult twig girdler chooses to lay her eggs on a limb that is a half inch or less in diameter. She makes a small slit in the bark of the limb and lays a single egg in the slit. She lays three to eight eggs on a single limb.

The female twig girdler will live six to 10 weeks and lay 50 to 200 eggs. After she lays her eggs on a limb, she will move down the limb 18 to 20 inches and chew a continuous notch around the limb, girdling it. This will kill the end of the limb, which will break off and fall to the ground.

The reason that the twig girdler kills the end of the limb is that the larva is unable to develop when sap is flowing in the limb. When the limb falls to the ground, the egg hatches and the larva start to develop.

During fall and winter, the larva go into a dormant state, but in the spring they grow rapidly. They feed on the woody portion of the limb and tunnel toward the cut end of the branch. The larva finish development in early September to emerge as adults and start the process all over again.

There are a number of trees in our area that can be affected by twig girdlers. The trees that are attacked the most are hickory, pecan, persimmon, elm and hackberry.

This year, the population has been high. I have seen oak trees, dogwoods and some fruit trees that have been attacked. These are trees that are usually attacked only when there are large numbers of twig girdlers.

The damage from twig girdlers is not going to kill a tree, but it can cause structural problems. In young trees, if the central leader is damaged, it can slow down or stop the growth of the tree. In older trees, they can have a flush of growth the next spring in the areas where the limbs were pruned.

Sanitation is the best way to control these insects. When you find limbs that have been damaged, pick them up and destroy them by burying, chipping or burning them. Any of these methods will destroy the larva. There is no effective chemical control for this insect. If we had a control, you would have to spray the tree every two to three weeks.

Ladybugs invade

They're back. I am talking about the invasion of the ladybugs. Ladybugs move into our homes as temperatures fall.

The Asian ladybug was imported to the United States in the late 1970s to eat aphids on pecan trees. Aphids are the small oval insects that feed on leaves, sucking the sweet sap out of the plants. Some people call them plant lice. Ladybugs love to eat aphids.

In Asia, these Asian ladybugs overwinter on rock walls. In the U.S., they enter our buildings and gather on walls and ceilings.

The best way to keep them out of your home is to repair or seal any openings where they can enter your home.

You can replace the weather stripping around your doors, caulk around your windows and seal any holes where pipes or wires come into the house.

If ladybugs do enter your home, you can sweep them up and put them back outside away from your house.

Ladybugs are great at controlling soft-bodied insects that attack our plants, so we need to try and save as many as we can.

Columbia County Extension Agent Charles Phillips can be reached at (706) 868-3413 or by e-mail at charlesp@uga.edu.