Boxelder bugs are common red-and-black garden insects often seen on boxelder, maple, and ash trees. They become especially noticeable in fall when they gather on sunny sides of buildings. Homeowners often wonder, Do boxelder bugs damage plants?, The answer is mostly no, but understanding their habits is key to protecting your garden.
In this blog post, we will explain how boxelder bugs feed, which plants they target, the signs of damage, and effective control methods. We’ll use friendly, easy-to-understand language to help the general reader spot boxelder bugs and manage any impact on plants.
What Are Boxelder Bugs?
- Description: Adult boxelder bugs are about ½ inch long, black with reddish-orange markings on the back and sides. Nymphs (young bugs) are bright red with black legs.
- Life cycle: These true bugs feed on trees in spring and summer and seek shelter in cracks or homes for winter. They lay eggs on tree bark in spring; nymphs hatch and feed, molting through stages to become adults by summer.
- Nuisance behavior: Boxelder bugs are notorious for clustering in large numbers on walls and houses in autumn and winter. They do not bite people or pets, but can be unpleasant if crushed (bad odor, stains). Most problems are due to their sheer numbers or stains, not plant damage.
Boxelder Bugs’ Feeding Habits
- Piercing-sucking mouthparts: Boxelder bugs feed by inserting needle-like mouthparts into plants. They mainly suck sap (plant fluids), rather than chewing leaves. This feeding can remove fluid from new leaves and suck seeds. Over time, heavy feeding may distort foliage or yellow the leaves (chlorosis). When this happens, Boxelder bugs damage plants, affecting their overall health.
- Favorite food sources: Their number one target is female boxelder trees (Acer negundo), which produce seed pods they love to eat. They also feed on young leaves of boxelder and related maples, and sometimes on ash trees. Fruit trees like apple, peach, cherry, and even grapes can be nibbled on during heavy infestations.
- Other host plants: In gardens, boxelder bugs have been found on strawberries, raspberries, and other berries, though these cases are less common. Overall, they prefer trees that produce small seeds or pods.
Do Boxelder Bugs Harm Plants and Trees?
- Generally harmless to plant health: Most experts agree that boxelder bugs cause minimal damage to healthy plants. They are considered “nuisance pests” rather than destructive ones. For example, Minnesota Extension notes they “don’t cause meaningful damage to plants or trees,” and Prairie Ecologist explains they “don’t siphon enough to hurt the trees.” However, it’s important to note that Boxelder bugs damage plants in subtle ways through their feeding habits, especially when infestations are large.
- Minor cosmetic damage: While not fatal, heavy boxelder bug feeding can cause subtle damage: new leaves may curl, yellow, or develop red/brown spots where the bug has fed. Fruits (especially soft stone fruits and apples) may show small pits or dimples on the surface after multiple punctures. These symptoms are usually cosmetic; the plant’s overall health and fruit production are rarely affected in home gardens.
- Effect on seeds and young plants: By feeding on seeds and flower buds, boxelder bugs can slightly reduce seed viability or deform young fruits. In commercial orchards, large infestations have been known to create marketable defects in fruit. In a backyard or landscape, this is seldom a big issue, but it can be noticeable if bugs are very numerous.
- Tree bark and wood: Boxelder bugs do not bore into wood or dig into bark. They use bark crevices to lay eggs in spring, but this does not harm the tree. No girdling or deep bark damage occurs – their harm is limited to surface feeding.
Signs of Boxelder Bug Damage
- Leaf symptoms: Look for yellow or brown speckles on leaves, often along veins or edges, and slight leaf curling or distortion where bugs have fed. On maple or boxelder trees, you might see areas of leaves fading or turning pale green. These symptoms appear after the bugs have been present in large numbers.
- Fruit and seed damage: Check developing fruits and seed pods. You may notice small, rough indentations or pits on apple skins or stone fruits where boxelder bugs have punctured the surface. Seeds in pods may be partially eaten or shriveled. These marks are usually minor and not as severe as the large holes cut by caterpillars or beetles, but Boxelder bugs damage plants by feeding on the seeds and fruit, potentially affecting their appearance and quality.
- Droppings (frass): Heavy infestations sometimes leave tiny black or dark green droppings on leaves or fruit. However, boxelder bug frass is not often obvious unless they numbers in the hundreds on a plant.
- Presence of bugs: The most telltale sign is simply seeing the bugs themselves – adults are easy to spot (black/red, about ½ inch), often clustered together, and nymphs are bright red. If you see many adults on a plant, damage may soon follow.
Common Plants Affected by Boxelder Bugs
- Boxelder trees: These female trees (with seeds) are the boxelder bug’s favorite. Almost every boxelder bug sighting in spring/summer is on these trees. Since boxelder bugs feed on the seeds and leaves, Boxelder bugs damage plants like boxelder trees by feeding heavily on them, especially during their reproductive season.
- Maples: Especially red maples and silver maples, young leaves and seeds (samaras) can attract bugs. Maples without boxelder trees nearby may still host boxelder if the bugs wander from other areas.
- Ash trees: Occasionally attacked, especially white ash near box elders. The bugs may feed lightly on leaves when boxelder is plentiful.
- Fruit trees and berries: Apple, pear, peach, cherry, and other fruit trees can get nibbled on by heavy boxelder bug populations. Small berries (strawberry, raspberry) are sometimes mentioned by arborists, though this is less common than tree feeding.
- Plants growing near boxelder trees: Gardens adjacent to female boxelder trees often see more boxelder bugs. Ladybugs and moths may travel between host trees and nearby plantings, so if a boxelder tree is next to an herb/vegetable garden, some bugs may stray onto those plants.
- Lawn and non-host plants: Boxelder bugs do not feed on grass, flowers, or most vegetables. They may walk across them, but they won’t cause damage to non-host plants.
Boxelder Bug Infestations in the Garden
- When infestations occur: Most boxelder feeding happens in spring and summer when leaves and seeds are new. However, in late summer/fall, they begin congregating to overwinter. At this stage, they may also appear on fruit trees and garden plants. Infestations (large populations) tend to follow warm, dry seasons or heavy seed years for host trees.
- What an infestation looks like: You might suddenly see dozens or hundreds of bugs on your trees, shrubs, or even the ground. They often cluster on sunny spots or on the southeastern side of trees and buildings. Many bugs mean more visible damage (more yellowing or spotted leaves).
- Potential garden impact: In most cases, a boxelder bug infestation is a visual nuisance, hundreds of bugs crawling on plants. Actual harm to the plants is usually limited: the foliage may have yellow specks (as noted above), and some fruit surfaces may be marked. Very occasionally, a severe infestation on a very young or stressed plant could weaken it slightly, but this is rare.
- Interaction with other pests: Because they are so abundant, boxelder bugs can be mistaken for more destructive pests. It’s important to correctly identify them (versus stink bugs or leaf-footed bugs) before acting.
- Overwintering behavior: In fall, boxelder bugs often move off plants to seek shelter. They may congregate on outer tree bark or leave plants entirely to head indoors. So, garden infestations typically decline by winter, but that’s when they become indoor pests.
Are Boxelder Bugs Harmful to Trees?
- Short answer, not really: Boxelder bugs do not girdle or kill trees. Healthy, mature trees generally tolerate boxelder bug feeding easily. Most university extensions emphasize they are “nothing more than an annoyance” for trees.
- Seed-bearing trees: If you have female boxelder trees, heavy bug feeding may slightly reduce the number of viable seeds those trees produce (bugs eat the seeds or larvae within). For maples or ash, which usually don’t rely on those specific seeds for regeneration, the impact is negligible.
- Small or young trees: Seedlings or very young saplings might be more vulnerable if hundreds of bugs are sucking on tiny leaves. In practice, however, even young trees rarely show long-term effects. Their ability to photosynthesize (make energy) from leaves isn’t typically compromised by the small amount of sap lost to boxelders.
- Long-term tree health: No studies show boxelder bugs
significantly weaken trees or cause lasting health problems. Tree experts recommend controlling the bugs more for aesthetic reasons and to reduce the “pastiness” than to prevent tree health decline.
How to Prevent Boxelder Bug Damage to Your Plants
While boxelder bugs typically don’t harm plants or trees enough to warrant drastic action, their presence can still be disruptive. To minimize the risk of Boxelder bugs damaging plants, consider these measures:
- Seal entry points: For homes, make sure windows, doors, and cracks in the building are sealed to keep bugs from coming inside during fall and winter.
- Remove them by hand: When bugs appear on your plants in fall, use a broom to sweep them away or vacuum them up. Regular maintenance of plants and their immediate environment will help.
- Use insecticidal soap: If infestations grow large, you can use insecticidal soap or a contact insecticide in your garden (be sure to follow all instructions for safe use).
- Plant resistant varieties: Consider planting non-boxelder or non-maple trees near your garden. Boxelder bugs avoid other types of trees, and this may limit their presence.
Conclusion
Boxelder bugs are generally harmless to your plants but can be a nuisance due to their clustering and occasional minor damage to leaves and fruit. While they rarely cause significant harm, Boxelder bugs damage plants by feeding on seeds and foliage, leading to cosmetic issues. By understanding their habits, you can take simple steps to manage their impact. If you need expert help in keeping boxelder bugs away from your property, Vanquish Pest Control is here to assist!
For more tips or to schedule a pest inspection, visit Vanquish Pest Control.
FAQs
What attracts boxelder bugs to my garden?
Boxelder bugs are attracted to boxelder, maple, and ash trees, particularly when these trees produce seeds or sap in spring and fall.
Do boxelder bugs cause long-term damage to trees?
No, boxelder bugs rarely cause lasting harm to healthy trees. They may cause minor cosmetic damage, but nothing that affects the tree’s overall health.
How can I prevent boxelder bugs from entering my home?
Seal cracks and openings around windows, doors, and vents. Use weather stripping and caulk to prevent bugs from getting inside during the winter months.
Should I use pesticides for boxelder bugs?
Pesticides can be used if infestations are severe. However, non-chemical solutions like hand removal or vacuuming are safer and more environmentally friendly options.
Can boxelder bugs bite people or pets?
No, boxelder bugs do not bite people or pets. However, they can emit a foul odor when crushed, and their presence can be bothersome.