Lilac/Ash Borer

Lilac/ash borer is an extremely common wood borer found throughout North America. The larvae will tunnel into the lower branches and trunks of ash trees, causing injury and nutritional problems. It’s difficult to see if you have a larvae problem at first, since the burrowing and feeding usually takes place around the soil line, although some signs can be spotted about 10ft off the ground.

The Life of the Lilac/Ash Borer

An ash borer will spend most of the winter in the tunnels it has made, coming out for feeding in the early spring. The adults will only start to emerge when the temperatures are at least 60F, so the exact time of year will depend on the climate of the area. You may see the moths flying during the day, unlike most others. The females will lay their eggs around the lower trunk of the trees. Most will deposit all eggs within the first week they emerge from the tree, as adults don’t live too long due to various prey, parasites, and infections. After around two weeks, the eggs will hatch and the larvae will start feeding. You may see irregular holes that are 1-3cm wide, where the larvae travel into the trunk for food. During the winter, the larvae produce a pupal chamber which is thin enough for adults to easily push through in the spring.

Knowing You Have Ash Borers

At first it will be difficult to spot signs of the insects, as the holes are irregular and low down. However, ash trees will start to show signs of decay in the bark and around the mid- to upper-crowns, as the tunnels prevent nutrients spreading across the tree. Some trees become so weak that they break, although death to the trees is uncommon with the lilac/ash borer. If you suspect lilac/ash borer infestation on your ash tree, contact SprayTech for treatment options.