| Common Name | Scientific Name |
|---|---|
| Boxelder Bug | Boisea trivittatus (Say) |
Boxelder bugs may invade buildings, especially during the warm days of autumn, to seek shelter sites for overwintering. They are attracted to lights and will readily fly in open doors and windows. Indoors, these bugs are a nuisance by their presence, produce a foul odor when crushed and may stain curtains with fecal matter. Outdoors, they can be found clustering in large numbers on the sides of trees, buildings and other structures. Large populations are often correlated with long, hot, dry summers. During warm winter and spring days, they may become active, moving from their hiding places into living spaces. Although they do not cause damage to buildings, clothing, food or humans, populations are annoying.
Adult boxelder bugs are flat-backed, elongate, narrow, about 1/2 inch long, 1/3 inch wide and dark brownish-black with three lengthwise red stripes on the pronotum (area behind the head). The head is black with the "beak" or proboscis reddish-orange and the long, thin, four-segmented antennae, half as long as the body. Wings are thick and leathery at the base and membranous at the tip. There are red veins in the wings and the abdomen is bright red under the wings. The nymphs or immatures resemble the adults in shape except they are smaller, more rounded, wingless and bright red. Eggs are dark reddish-brown.
During the autumn months (around October 1), adult and large nymph
boxelder bugs congregate in large numbers primarily on the bark of
boxelder trees and then begin migrating to a place for overwintering
(frequently around foundations and windows). Only full-grown adults
overwinter, moving to hibernation sites either by crawling or flying.
They may crawl from a nearby tree or fly about two miles to find
shelter. These bugs hide in cracks and crevices in walls, in door and
window casings, around foundations, in stone piles, in tree holes and
in other protected places. On warm days during winter and early
spring, they sometimes reappear on light-painted surfaces outdoors on
the south and west sides of the house, resting in the sun.
Overwintering adults leave their hibernating quarters with the coming of warm weather (last week of March), and females begin laying eggs (late April to early May) in crevices of tree bark, stones, leaves, grasses and on other objects near host plants. Eggs hatch in 11 to 19 days, with bright-red nymphs appearing about the same time new tree leaves develop. There are five nymphal instars. The instars get progressively darker red with each stage. In July, new adults lay eggs that result in a second generation by early autumn. Boxelder bugs feed primarily on the seed-bearing boxelder trees by sucking sap from the leaves, tender twigs and developing seeds. Occasionally, they have been observed feeding on ash, maple, plum, cherry, apple, peach, grape and strawberries, causing some scarring or dimpling of fruits. However, boxelder bugs seldom develop in large enough numbers to become a nuisance, unless able to feed on seed-bearing boxelder trees. Apparently, they do little actual feeding damage to boxelder trees. There may be one to two generations per year.
Since boxelder bugs feed and reproduce primarily on pistillate (female) boxelder trees, removal of these trees, especially around the house, would eliminate nuisance populations. Some towns have outlawed pistillate trees. However, adults are capable of flying two or more miles for suitable hibernation quarters. If boxelder trees are desirable for shade, ornamental beauty or other purposes, use only propagation (cuttings) from the staminate (male) trees. Eliminate potential hiding places such as piles of boards, rocks, leaves, grass and other debris close to the house. Rake leaves and grass away from the foundation in a six- to ten-foot-wide strip, especially on the south and west sides of the structure. Be sure to caulk and close openings where boxelder bugs can enter the house such as around light fixtures, doors and windows, unscreened vents, holes in walls around utility pipes or conduits, air conditioners, heat pump lines and through the foundation. They are also attracted to lights and can fly in open doors or windows. Screen all windows, doors, crawl spaces, exhaust and roof vents and louvers. Clusters of bugs may be killed by pouring boiling water on them. Be careful to avoid killing grass and other desirable plants with boiling water.
Should boxelder tree removal be impractical, treat the young, exposed boxelder bugs "nymphs" on the trees during spring and early summer to prevent potential large populations and indoor migrations in the autumn. Some homeowners report effective, cheap control by spraying a soap mixture on the nymphs and adults as they begin congregating in late summer. The spray consists of about 1/2 cup of a laundry detergent in one gallon of water applied by a hand sprayer or squirt bottle directly on the boxelder bugs as often as necessary. The soap mixtures kills only the bugs sprayed, but does not prevent others from coming to the site. Test the mixture first on an inconspicuous spot before application as it might stain cedar and other siding. Applications of acephate (Orthene), carbaryl (Sevin) or chlorpyrifos (Dursban) sprayed to tree trunks, limbs and foliage are effective. Other sprays include amorphous silica gel (Drione, Tri-Die), diazinon and pyrethrins (Exciter, Microcare, Pyrenone, Synerol). Sprays can be applied on foundation walls, sidewalks, fence rows, etc. as boxelder bugs mature and migrate from the trees. Cracks and crevices, wall voids and similar areas may be treated with dusts and/or aerosols. Dusts labelled include amorphous silica gel (Drione, Tri-Die), boric acid (Perma-Dust) and diatomaceous earth (Answer, Organic Plus). Only the licensed pest control operator or applicator can use "Restricted Use" pesticides such as cyfluthrin (Optem, Tempo), cypermethrin (Cynoff), propetamphos (Safrotin) and certain formulations of permethrin (Astro, Dragnet, Flee, Prelude, Torpedo). When applications are needed on tall trees or large areas requiring specialized equipment, it is best to employ a reputable pest control firm. Indoor control is often difficult since the bugs may be scattered throughout the house. Household aerosol pressurized sprays containing pyrethrins will give temporary control. When applying these materials, fill the entire room with a mist spray and close it off for several hours. Later, use a vacuum cleaner and/or broom and dustpan to pick up dead and dying bugs.
This publication contains pesticide recommendations that are subject to change at any time. These recommendations are provided only as a guide. It is always the pesticide applicator's responsibility, by law, to read and follow all current label directions for the specific pesticide being used. Due to constantly changing labels and product registration, some of the recommendations given in this writing may no longer be legal by the time you read them. If any information in these recommendations disagrees with the label, the recommendation must be disregarded. No endorsement is intended for products mentioned, nor is criticism meant for products not mentioned. The author, The Ohio State University and Ohio State University Extension assume no liability resulting from the use of these recommendations.
All educational programs conducted by Ohio State University Extension are available to clientele on a nondiscriminatory basis without regard to race, color, creed, religion, sexual orientation, national origin, gender, age, disability or Vietnam-era veteran status.
Keith L. Smith, Associate Vice President for Ag. Adm. and Director, OSU Extension.
TDD No. 800-589-8292 (Ohio only) or 614-292-1868