Three-Lined Fig Tree Borer
By George Giltner, Master Gardener
The three-lined fig tree borer, Ptychodes trilineatus, is the common wood borer of figs in the South. Its range is from Texas to Florida and down into Central America.
The adult is large, mainly glossy black and has three white stripes. As with other borers of Cerambycidge, the antennae are very long. They feed on all parts of the fig above ground to include the leaves, stem, and fruit. However, most damage to the fig tree occurs after they lay eggs in the bark of the tree. The flat-headed white larvae immediately began damaging the tree by boring through branches and then into the trunk. They feed continuously on wood for three months to a year and then pupate.
Trees which are most susceptible are those with dead wood, wounds, knots, and old wood. They prefer wood that is not flowing with sap, like a transition between dead and live wood. However they will infect and thrive in any tissue region of the tree.
Unfortunately an infection with the three-lined fig tree borer is a death sentence to the tree. The larvae are immune to chemical insecticides. Trimming of the tree just leads to more available infective sites. Usually larvae are spread throughout the wood in the tree. Therefore the tree should be cut and burned. Then plant a new variety and provide optimal soil, placement, and water conditions for a healthy and fast growing tree. Borers will mostly attack trees that are weak or that have damage to old wood.
Editor’s Note: George Giltner is a Louisiana Master Gardener in Beauregard Parish, and is a self-taught entomologist.