Box elder bugs (Boisea trivittata) are common insects often recognized by their black bodies and distinctive red or orange markings. They frequently become a household nuisance, not because they are destructive, but because they gather in large numbers, particularly as seasons change. Understanding their dietary preferences is the most effective way to manage their presence on a property. This insect has highly specialized feeding habits that dictate where they live, what they consume, and, perhaps more importantly, what they ignore. This article explores the specific plant tissues that sustain these bugs and clarifies the materials and plants they do not eat.
The Core Diet: Box Elder and Maple Trees
The entire life cycle of the box elder bug is fundamentally linked to a specific group of trees, primarily the female box elder (Acer negundo). These trees are the preferred host because they produce the seeds, or samaras, that contain the highest concentration of nutrients for the insects. Box elder bugs possess piercing-sucking mouthparts, known as a proboscis, which they use to penetrate plant tissues and extract fluids, rather than chewing the material itself.
The nymphs and adults target developing seeds, tender new leaves, and young stems of the female box elder tree to access the sugary sap and nutritious fluid within. This feeding behavior is most pronounced in late spring and early summer when the host tree is actively producing new growth and seeds. The bugs will also feed on other members of the maple family, such as silver maples, especially when their preferred food source is less available.
Occasionally, the bugs may also feed on ash trees, though this is less common than their association with maples. Their feeding on these trees is not considered significantly damaging, as the extraction of sap typically causes only minor, cosmetic issues like leaf distortion or slight discoloration. The ability of the box elder bug to thrive is directly tied to the presence of seed-bearing female box elder trees.
Seasonal Shifts in Feeding and Hydration
The box elder bug’s feeding strategy changes dramatically as the year progresses, shifting from a focus on nutrition to a search for survival resources. Throughout the summer, young nymphs and newly matured adults actively feed on the seeds of host trees to build up fat reserves for the coming colder months. This active feeding period ensures they have the energy required for the non-feeding phase of their life cycle.
As late summer transitions into fall, the bugs’ primary motivation changes from eating to finding warm, dry shelter for overwintering. They congregate in large numbers on the sunny, south-facing sides of rocks, trees, and homes to bask and prepare for migration. During this transitional phase, they may opportunistically feed on fallen fruits, piercing the skin to suck out the juices:
- Apples
- Plums
- Grapes
- Cherries
Once they move into a sheltered location, such as wall voids, attics, or crevices, they enter a state of dormancy and do not eat throughout the entire winter. Their presence inside a home is purely for warmth and protection from the cold, not to find new food sources within the structure.
Dispelling Myths: What Box Elder Bugs Avoid
A frequent concern among homeowners involves the potential for box elder bugs to damage property, but their specialized diet prevents them from consuming most household materials. The bugs do not eat or damage structural wood, and they are not considered wood-destroying pests like termites. Their mouthparts are simply incapable of breaking down the tough fibers of wood or other hard materials.
Box elder bugs also avoid household fabrics, clothing, and stored pantry foods. They are not equipped to digest or extract nutrients from these items, unlike many other common household pests. Similarly, common garden vegetables, ornamental plants, and houseplants are generally safe from box elder bug feeding.
Any damage they cause is limited to the cosmetic discoloration of their host trees or minor dimpling of soft fruit. The most significant issues they cause in a home are their sheer numbers and the reddish-orange stains they can leave behind if they are crushed.