Borers are incredibly frustrating pests, even more so for the fact that they are difficult to see. As their name suggests, they burrow into tree trunks and plant stems, happily nibbling their way through the crucial inner structures. Borers may be beetles, moths, or wasps—the larval stage is when an insect bores to feed. Specific species of borers may impact certain plants, such as squash vine borers and the infamous emerald ash borer. Learn how to spot the signs and deal with these pesky bugs.
The best way to prevent pests in general is to maintain healthy plants. Practice crop rotation in your garden so that borers can't return to the same host plant again in following years. Place a protective ring of mulch around the base of a tree trunk or over plant stems. Other physical barriers may include cloth or burlap wraps.
Unfortunately, borers can kill a plant if not caught early. It's always good practice to inspect your plants for pests and diseases regularly. Borer damage may manifest itself as suddenly wilted branches or stems, leaf discoloration, canopy dieback (in trees), and odd swellings on branches and trunks (similar to galls). Look for entry and exit holes, which may be accompanied by frass, a wispy material that looks like sawdust. When bark is peeled back, you might encounter feeding damage in the form of snaking trails.
If you do find that borers have gotten to your plants, you have several options. Borers that target specific plants may lay eggs on the leaves early in the growing season. If you spy eggs, scrape them off and dump them into a bucket of soapy water. If the plant is infected only in one section, cut away that branch or vine and properly dispose of it by burning or chipping. If you see only one or two entry holes and suspect you can locate the borer(s), make a small vertical cut along the stem and pluck the borer out. If you must use an insecticide, opt for an organic one that won't accidentally kill beneficial organisms.