Grub Insect Found in Trees
- Adult flatheaded borers are boat-shaped and metallic. Generally colorful, they range from 1/3 to 1 inch in length. Grubs can be 1/4 to 2 inches long. They are yellowish and legless with a flattened segment just behind the head. Flathead borers are dangerous pests of established shade and ornamental trees. Typically attacking the sunny side of the tree, they excavate winding galleries under the bark and potentially girdle and kill a tree.
- Roundheaded borers chew straight through the tree and into the heartwood. As they feed and excavate, they leave behind droppings, called frass, and sawdust. This litter often accumulates around the bottom of the tree. Adults are called longhorned beetles because their long antennae resemble horns. They are between 1/4 and 3 inches long. Larvae are slender, have no legs and are white to yellowish. Depending on the beetle, larvae can live in the tree from several months to three years.
- Keeping trees healthy is the best way to prevent grub infestation. Keep trees irrigated during droughts. Contact a local university extension regarding a soil test to ensure you are using the proper fertilizer in the correct amounts. Keep trees pruned of dead and damaged wood, and avoid damage to trees by lawnmowers, weed trimmers or other gardening tools. Wrap the trunks of young or transplanted trees with burlap, nursery wrapping paper or newspaper to prevent egg laying.
- If chemical control is necessary there are several products available to employ. Never apply pesticides to wet bark, and always follow manufacturer's instructions. Products containing chlorpyrifos are effective but should not be used around homes. For concentrated formulas, bifenthrin and endosulfan are effective. Pyrethroids can be effective but may require weekly applications. For flathead borers, try products containing chlorantraniliprole and imidacloprid.