Types of Bore Bugs

Insect borers can cause serious damage to trees, vegetables and shrubs by burrowing into the structure of the plant and destroying the tissue. Both larvae and adult borers tunnel into plants, and they often lay their eggs there as well. Some borer infestations can be hard to identify, but clues include small holes in the structure and death of the plant or part of the plant.

Bark beetles are specific to trees, where they bore beneath the bark. The beetles are small, cylindrical in body shape and dark in color. Larvae are cream-colored and legless. Signs of bark beetle infestation include a powdery sawdust-like material, beetle excrement, which accumulates around entrance holes in the bark, sap leakage from entrance holes, and multiple exit holes that give the tree a "gunshot" look. Limiting the transport of firewood and brush can curb the spread of tree borers. Examples of bark beetles include: southern pine beetles, emerald ash borers, ambrosia beetles, eastern ash bark beetles and black turpentine beetles.

Long-horned beetles are adult borers with antennae that make the bug look like it has horns. Round-headed borers are the larval stage of the same species, but they have not yet developed antennae. These beetles bore into the wood and beneath the bark of trees and shrubs. Their tunnels are oval or round in shape. The larva produces frass as it tunnels. Frass is sawdust-like excrement that builds up in the tunnels, and is sometimes pushed out of the entrance holes. Visible frass is a sure sign of a borer. (See Reference 1)

Metallic wood-boring beetles get their name from their adult coloring--shiny shades of bronze, copper, green and blue. The adults have a flat, hard, bullet-shaped body and small antennae. Larvae are called flat-headed borers because of a flattened body segment just behind their heads. The beetle and borer both make either round or flattened winding tunnels through the wood of weakened trees and shrubs.

Weevils tend to bore into ornamental plants like palms, grain plants like rice or crops like cotton more often than tree woods. Adult weevils have a characteristic snout on the front of the head where the mouth is located. They bore into plants with their chewing mechanism located at the end of the snout. Females may lay eggs in the hole openings, creating what looks like a wart on the plant. Weevil damage can affect the production of the plants it infests.

Borer insects that infest vegetable crops include the squash vine borer and European corn borer. European corn borers feed on the stem or fruit of many vegetable species, but especially corn, peppers and Irish potatoes. The young corn borer is a caterpillar nearly an inch long. Adults become light yellow moths with dark banding on the wings. Squash vine borers are caterpillars that bore into squash and pumpkin vines, and can cause serious damage. The caterpillar is thick and white with a brown head; the adult is a moth with greenish metallic colored wings.