The willow borer is a pest that attacks willow trees and other deciduous plants. Willow trees are susceptible to infestation by this beetle, as well as poplars, cottonwoods, aspens, lindens, and other deciduous trees. The adult willow borer is a small black beetle with orange legs and antennae, while the larvae are white grubs with brown heads that live inside the wood of the tree.
The adult female willow borer lays her eggs in bark crevices of healthy shoots or branches of the tree. These eggs hatch after several weeks into larvae that bore into the wood of the tree and feed off it for up to three years before coming to the surface to pupate into adults. During this time period, they cause damage to the plant by weakening its structure and preventing it from getting enough nutrients from sunlight for healthy growth.
As one of the most destructive pests in North America, the larvae of the willow borer moth can cause irreparable damage to your yard and landscape. This is why it’s important to prevent willow borers with beneficial insects and organic insecticides for willow borers. There are two types of organic insecticides for willow borers, soil drenches and foliar sprays. Another type of organic insecticide for willow borers is biological control using the parasitic wasp ( Trichogramma minutum ), but this method takes time before it starts working.
Wood boring insects on willow trees can cause significant damage, particularly because infestations often go unrecognized or are confused with other problems. Identify wood borers that choose willows as hosts as well as the problems they cause and effective control methods. Provide proper care to your willow trees to increase the potential for infestation avoidance or management.
How To Manage Willow Borer
Willow borers are a common insect that can be found in the United States. They make holes in willows, and they create webs around their holes to protect themselves from predators. Willow borers are considered pests because they destroy willow trees by eating away at their trunks.
This pest is also known as an invasive species because it is not native to North America. However, it has been found in every state except Hawaii and Alaska. It can be found on a variety of trees including willow, poplar, and birch trees as well as many types of woody shrubs such as elderberry bushes and rose bushes.
Willow trees (Salix species) are reasonably easy to maintain; providing the care they need to avoid borer infestations is often a sufficient method of control. Grow willow trees in a location that provides full sunlight to extremely light shade, according to the University of Florida IFAS Extension. Willows will thrive in moist soils, but good drainage is key. Waterlogged soil provides ideal grounds for fungal infections that leave trees in decline and open to insect problems. Nearly all soil types are acceptable but avoid extreme alkalinity or acidity.
- Wood boring insects on willow trees can cause significant damage, particularly because infestations often go unrecognized or are confused with other problems.
- Willow trees (Salix species) are reasonably easy to maintain; providing the care they need to avoid borer infestations is often a sufficient method of control.
Cottonwood borers (Plectrodera scalator) are widespread wood-boring insect pests on willow trees, according to Kansas State Research and Extension. These insects also cause problems for cottonwood and poplar trees. These borers are long-horned beetles that, in the larval stage, display cream-hued bodies that reach a length of up to 1 1/2 inches. Adults reach up to 1 1/4 inches and display bodies in black with stripes of white hair.
Symptoms and Damage
Wood-boring insects on willow trees feed in both their larval and adult stages. During the end of spring and throughout summer, adults feed on new willow growth and chew holes into bark near the soil line into which they lay their eggs. Within two weeks, the larvae hatch and tunnel into the trunk or soil. Unfortunately, growers may not notice the problem or may think the damage is associated with other pests like woodpeckers, according to the Texas Agricultural Extension Service. Look for holes as well as a residue that resembles sawdust as a sign of borer infestation. Adult damage includes the death of shoots that often fall to the ground. Larvae feed on and near roots, often destroying internal plant tissue resulting in severe decline, collapse, or tree death.
- Cottonwood borers (Plectrodera scalator) are widespread wood-boring insect pests on willow trees, according to Kansas State Research and Extension.
- Within two weeks, the larvae hatch and tunnel into the trunk or soil.
Cottonwood borers are considered a “secondary” infestation because they often invade trees that are already ill. Preventive management often inhibits infestations from occurring. Prepare a cultural environment that adheres to your tree’s needs by avoiding extreme wind, stress, and cold injury, when possible. Avoid creating wounds on trees through proper pruning and careful mowing. Sanitize tools such as pruning shears between each cut and each use to prevent disease transfer. If your tree experiences a problem, remove and collect affected plant parts, according to the Texas Agricultural Extension Service.
For willow trees that are experiencing a wood-boring insect infestation, chemical control measures are effective, particularly in conjunction with care measures that create tree health and vigor, according to the Texas Agricultural Extension Service. For cottonwood borers, apply an insecticide with the active ingredient chlorpyrifos. Determine the egg-laying period for your region and apply the insecticide to all parts of the tree during this time. Since chemicals only provide control for up to 10 weeks, reapply as needed. Contact your county extension agent for assistance.
- Cottonwood borers are considered a “secondary” infestation because they often invade trees that are already ill. For willow trees that are experiencing a wood-boring insect infestation, chemical control measures are effective, particularly in conjunction with care measures that create tree health and vigor, according to the Texas Agricultural Extension Service.
What is The Best Remedy Against Borers?
The best remedy against borers is to use a preventive trunk spray. Presently three insecticides applied as bark sprays are used for the control of wood borers: bifenthrin, permethrin, and carbaryl. The optimal timing for preventive trunk sprays is at about the time when the adult stages of the wood borer are first present.
List Of Insecticide For Willow Borers
Willow borers can be treated with insecticides, but some insecticides aren’t safe for certain types of trees or shrubs. Before applying any insecticide, check with a local nursery or extension office to find out which ones are safe around your specific plant species.
Bonide (BND806) – Caterpillar and Worm Killer, Bacillus thuringiensis (Bt) Ready to Use Insecticide/Pesticide Spray (32 oz.)
- INSECT KILLER – This pest control is great for use on cabbage looper, hornworms, tent caterpillars, gypsy moths, bagworms, and many more.
- PROTECTS FRUITS, VEGETABLES, SHADE TREES & ORNAMENTALS – Designed for use on broccoli, cauliflower, kale, mustard greens, eggplant, pepper, melons, tomatoes, cabbage, shade trees, and ornamentals.
- DOESN’T HARM BENEFICIAL INSECTS – Kills worms and caterpillar stage insects while causing no harm to birds, earthworms, or beneficial insects, such as honeybees and ladybugs.
- FAST ACTING FORMULA – Must be eaten by worms or caterpillars to be effective. After ingesting, bugs immediately stop feeding and will die within 2-3 days.
- ORGANIC GARDENING – The active ingredient of the product is a natural strain of the bacterium Bacillus thuringiensis, which is a leading insecticide used worldwide. Approved for organic gardening, our product is safe for use around people and pets.
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- INSECT KILLER – This pest control is great for use on adelgids, aphids, bronze birch borers, emerald ash borer, leaf miners, scale, and many other species of bug. Will also prevent new infestations.
- SOIL DRENCH APPLICATION – Concentrate dissolves in water allowing the insecticide to move through the root zone. Once in the roots, it moves up through the tree or shrub providing protection from insects. Also provides protection for new growth.
- FOLIAGE PROTECTOR – Designed for use on listed fruit, nut, and ornamental trees and shrubs.
- WON’T WASH AWAY – Tree and Shrub Insect Control is rainproof within hours. For best results, spray with enough time for it to completely dry before it rains. Will not wash off after it has dried.
- EASY APPLICATION – The product quickly mixes with water and should be applied by pouring or with a backpack, compression, knapsack, or tank-type sprayers. Carefully read and use according to label directions.
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Price : $14.36
- Size: 16 OZ
- Thuricide BT Caterpillar Control concentrate is used by organic gardeners and is made from bacteria that are toxic to listed pests.
- Safe to use on all plants, vegetables, and edible crops.
- Very low toxicity to humans and pets.
- For large quantity discount consideration or to request a mixed multi-pack, please message us.
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The use of insecticides for willow borers is an effective way to protect your trees from the damage that these pests can cause.
Insecticides are available at most garden centers and hardware stores, and you can find a wide variety of options online. The best thing to do is talk to your local garden store about what will be best for your situation. They’ll know if there are any specific pests that are causing problems in your area, as well as what products have worked well in the past for their customers.
Once you’ve talked with a professional, make sure you read all of the labels carefully before applying any insecticides to your trees. If you’re not sure how to use something safely or correctly, don’t hesitate to ask them.