Boxelder Bugs

Monday, October 19th, 2015 by Bill Cowley

Boxelder bug in NJ

Physical Characteristics:

Boxelder bugs (boisea trivittata ) are black insects with reddish-orange markings on their backs. Their elongated, oval-shaped, body contains six legs. The markings on boxelder bugs usually include three stripes on the prothorax, the area right behind the head. When the bug is still, their wings lay flat over their bodies and overlap each other which makes it appear as if they have an ‘X’ on their back. The eyes and first segment of their legs are also red. The body of a boxelder bug is approximately half an inch long.

Origins of its Common Name:

Boxelder bugs get their common name from their attraction to the boxelder tree. The boxelder bug is usually found on or near female boxelder trees because they feed on the seed-bearing trees. When boxelder trees are scarce, boxelder bugs have been known to occasionally feed on seed-bearing silver maples and have been observed feeding on plum and apple fruits, causing some scarring or dimpling. The bugs use their piercing-sucking mouthparts to suck sap from the leaves, tender twigs, and developing seeds of host trees.


In spring, females that have successfully overwintered, emerge and begin to forage for food. They will eat for approximately two weeks before they look for a mate. Reproduction will not occur until the outdoor temperature is consistently seventy degrees Fahrenheit. Once mating has occurred, the female boxelder bug will lay red-colored eggs in the cracks and crevices of the boxelder tree’s bark. Each female will lay between 200 and 300 eggs. The eggs are usually distributed either singly or in clusters of about 10 eggs.

The nymphs will hatch from the egg in as little as ten days. The nymphs grow throughout the spring and will develop into sexually mature adults during the summer. Nymphs must molt five times before becoming an adult. The length of time spent in nymph stage is dependent on both the temperature and the availability of food. In some cases, when there is a warm spring, the adults that hatched in the spring will be able to mate and lay eggs during the summer. These eggs will hatch into the nymphs of a second generation. Most second-generation nymphs will be fully mature by September.

During the fall many boxelder bugs look for places to overwinter since they are ectothermic, and therefore must rely on external sources to provide their heat. Boxelder bugs have been known to fly up to two and a half miles in order to find a suitable place to spend the winter. Only adult boxelder bugs overwinter. If a boxelder bug is in the nymph stage when winter begins they will not survive.

Boxelder bugs look for sheltered areas where temperatures stay moderate. The natural overwintering location for boxelder bugs is in dead trees and in leaf debris. Large groups of these bugs will come together to congregate on the south side of rocks, trees, and buildings where the sun hits. When the large mass of bugs gathers, they will often migrate to nearby buildings or homes to overwinter. Boxelder bugs have a relatively short life span. Even if the bugs successfully overwinter, they are very unlikely to live longer than one year.


Boxelder bugs are native to the western and southwestern sections of the United States, however, they are now found across North America including parts of Canada and Mexico. The habitat preferred by the boxelder bug is deciduous and mixed forests and meadows. During the warmer seasons of spring and summer, boxelder bugs will be found living on boxelder trees, maple trees, and ash trees. By late fall, the boxelder bugs will often leave the trees to seek shelter for hibernation.

Boxelder bugs are not solitary bugs, in fact, they exist in large, gregarious groups. They hibernate together during the winter and when the temperature increases they often move together to look for food. This tendency causes many people to describe them as semi-social insects. However, unlike other social insects like bees and termites, the group of boxelder bugs have no structure or hierarchy.


Adult boxelder bugs feed on boxelder trees, ash trees, and maple trees. They eat the leaves, flowers, twigs, and seeds. They rarely, if ever cause significant damage to the trees on which they feed, however, there have been isolated reports of boxelder bugs damaging the fruit. They have been known to eat the fruits of apple, pear, peach, and plum trees. When boxelder bugs are in their nymph stage they feed on the juices found inside the seeds of the boxelder, ash, or maple tree. Although their primary source of nourishment is vegetation, adult boxelder bugs have been known to eat other boxelder bugs or eggs during molting. In some cases, they have also been observed eating dead insects such as cicadas or ground beetles.


Many different animals eat boxelder bugs. These animals include, but are not limited to, spiders, grasshoppers, mice, rats, birds, and praying mantises. Boxelder bugs may even prey on their own species with adult boxelder bugs eating nymphs during molting. Although the boxelder bug has a number of predators, they do have a number of survival tactics that they employ. First, the red markings on an adult boxelder bug’s body, as well as the red color of eggs and early nymph stages, are believed to be aposematic. Although they are not actually poisonous, the bright red color is similar to certain distasteful or poisonous animals so predators may avoid them for that reason. Another survival tactic that adult boxelder bugs possess is the ability to give off a foul odor if disturbed. These bugs have a pair of abdominal glands that release a very unpleasant smell to ward off predators. Lastly, boxelder bugs congregate in large numbers which may intimidate possible predators.

Encounters with Humans:

Boxelder bugs have not been deemed a commercial pest and they are not dangerous, but they can be a huge nuisance. They can invade homes in the winter in very large numbers. If they do invade a home they can leave nasty stains on carpets when they are squashed. They also are known to release a foul smell if they feel threatened.

Preventative Measures:

There are a few steps homeowners can take to prevent boxelder bug infestations. If you have boxelder trees in your yard, remove any fallen pods immediately. Keep your garden tidy in order to reduce the available shelter for boxelder bugs. Next, repair any cracks or openings in your walls, roof, and other areas of your home. If there are openings that cannot be repaired use a silicone or silicone-latex caulk to seal these areas. It is important to take special care near holes used for cable and electric hook-ups because these are common entry points for insects. 

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