Mayflower Bug: What It Is and What to Do

The “Mayflower bug” is a common nickname for the Boxelder Bug (Boisea trivittata), an insect native to North America. They are known for appearing in large numbers, particularly in the spring and fall. While their sudden presence can be alarming, these insects are harmless to people and property. Their primary goal is seeking warmth or a place to overwinter.

Identifying the Mayflower Bug

Adult Boxelder Bugs are about a half-inch long with a flattened, oval-shaped body. Their coloring is predominantly black with noticeable red or orange lines. These markings include three stripes on the prothorax, the segment behind the head, and outlines along the edges of their wings. When at rest, their wings overlap to form a distinctive ‘X’ shape on their backs.

Immature Boxelder Bugs, known as nymphs, look quite different from adults. When they first hatch, nymphs are about 1/16th of an inch and bright red. As they mature, they grow larger and develop black markings. It is common to see nymphs and adults together, especially during the summer and fall.

Behavior and Habitat

These insects primarily feed on the seeds of specific trees, most notably the female, seed-bearing boxelder tree. They also feed on other maples and ash trees, using their piercing-sucking mouthparts to drink juices from leaves and seeds. This feeding behavior rarely causes noticeable damage to the host trees.

Their seasonal movements bring them into contact with homes. In the spring, as temperatures warm, they emerge from where they spent the winter. Throughout the summer, they feed and reproduce, with populations peaking during hot, dry years. As fall approaches, they seek protected locations to survive the cold, congregating on sunny sides of buildings and finding their way inside.

These bugs are considered a nuisance pest. They do not bite, sting, or carry diseases, nor do they cause structural damage or reproduce indoors. The primary issues are their presence in large numbers and fecal matter that can stain light-colored surfaces like curtains and walls. Crushing them should be avoided, as it releases a pungent odor and can also cause staining.

Preventing and Managing an Infestation

The most effective approach to handling Boxelder Bugs is preventing them from entering your home. This involves inspecting your home’s exterior to find and seal potential entry points. Pay close attention to cracks in the foundation, gaps around window and door frames, and openings where utility lines enter. Applying caulk or weather stripping can block their primary routes of entry.

For bugs that have already gathered on your home’s exterior, physical removal is often sufficient. A strong spray of water from a garden hose can dislodge them from walls. Using a vacuum cleaner is another effective method for removing large clusters of the insects both outside and inside.

If bugs have made it indoors, use a vacuum for removal. Once vacuumed up, the bag or canister should be disposed of to prevent them from escaping back into the house. While insecticides are available for exterior treatment, they are a last resort. If used, apply them in the fall and follow all label directions carefully.