Life Cycle of Boxelder Bugs: A Fascinating Journey Unveiled

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Boxelder bugs are common insects found in many regions, often causing a nuisance when they gather in large numbers around homes and other structures.

They are typically associated with boxelder trees, but can also be found on ash and maple trees.

As these bugs are harmless to humans and pets, understanding their life cycle can help you manage their presence around your property.

The life cycle of boxelder bugs begins in the spring, when adults emerge from their overwintering sites and lay their eggs in crevices of boxelder bark, leaves, or other objects.

After about 11 to 14 days, these eggs hatch into wingless, red-abdomen nymphs, which then develop in stages throughout the summer before becoming adults.

You may see boxelder bugs at various stages of their development during the warmer months, with population spikes more likely during hot, dry seasons.

One crucial aspect to note is that boxelder bugs tend to congregate in large numbers on the south side of trees and buildings as the weather cools in the fall.

This behavior is an important factor to consider when planning control measures, such as sealing cracks and crevices or repairing window screens to prevent the adult bugs from entering your home.

Life Cycle of Boxelder Bugs


Boxelder bugs start their life as eggs, which are typically laid on seed-bearing female boxelder trees during the summer months.

These eggs eventually hatch into nymphs, which is the next stage in their life cycle.

  • Color: Yellowish-brown
  • Size: Approximately 1 mm in length
  • Duration: A few weeks before hatching


The hatched nymphs are smaller versions of adult boxelder bugs, with red and black markings.

These nymphs undergo several molting stages as they grow and develop throughout the summer.

  • Color: Red and black
  • Food: Sap from boxelder tree leaves and seeds
  • Development: Progress through several stages before reaching adulthood
Eastern Boxelder Bug


Adult boxelder bugs are easily recognizable by their distinctive black and red markings.

These bugs reach about ½ inch in length when fully grown. Adults are capable of reproduction, laying eggs to begin the next generation.

  • Size: Approximately ½ inch in length
  • Appearance: Oval, black with red or orange markings on wings and body
  • Reproduction: Adults reproduce in the summer, laying eggs on boxelder trees

Comparison of Boxelder Bug Life Cycle Stages:

Stage Appearance Size Diet
Egg Yellowish-brown ~1 mm N/A
Nymph Red and black Smaller Sap from boxelder leaves and seeds
Adult Oval, black with red markings ~½ inch Sap from boxelder leaves and seeds


Boxelder bugs have a relatively short lifespan.

After hatching from eggs in the spring, they undergo several nymphal stages throughout the summer, maturing into adults by late summer or early fall.

As adults, they seek out overwintering sites to survive the colder months. While many of these bugs perish during winter due to environmental factors, some survive to emerge the following spring and start the cycle anew.

On average, a boxelder bug’s lifespan ranges from a few months to a year, with most of their life spent in the adult stage.

Habitat and Host Trees

Boxelder Trees

Boxelder bugs (Boisea trivittata) primarily feed on boxelder trees (Acer negundo).

Female boxelder trees produce seeds that serve as a main food source for these insects.

In North America, boxelder trees can often be found near rivers and streams.

  • Common in North America
  • Found near rivers and streams
  • Female trees produce seeds

Ash Trees

Although their main host is the boxelder tree, boxelder bugs can also be found on ash trees (Fraxinus spp.) in some heavily infested areas.

Ash trees can serve as an alternative food source for boxelder bugs, providing sap from their leaves.

Maple Trees

Boxelder bugs are not only found on boxelder and ash trees, but also on maple trees (Acer spp.).

These insects feed on the sap of maple trees and can target both seed-bearing and non-seed-bearing trees, making them a more versatile host option for the bugs.

Boxelder Bug Nymphs

Comparison table:

Tree Type Main Host Seed-Bearing Trees Alternative Hosts
Boxelder Yes Female trees N/A
Ash No N/A Heavily infested areas
Maple No Both types Versatile host option

By understanding the preferred host trees of boxelder bugs, we can better comprehend their habitat and the factors that contribute to their population growth.

Seasonal Behavior


In spring, boxelder bugs emerge from their overwintering sites and start to feed on leaves and twigs of boxelder trees.

The adults lay eggs on leaves or bark, which hatch after about two weeks. Nymphs feed on newly formed plant tissues.


During fall, large populations of boxelder bugs congregate on the south side of trees and buildings to find warmth.

As temperatures drop, they begin to seek shelter inside homes, becoming a nuisance pest. They enter through cracks or crevices, damaged window screens, or insulation gaps.

Common entry points:

  • Cracks and crevices
  • Damaged window screens
  • Insulation gaps
Mating Boxelder Bugs


Boxelder bugs spend the winter months in hibernation within homes or other protected areas.

Most of the overwintering adults die off in cold weather without needing any chemical intervention. Proper home sealing can prevent entry and reduce infestations in the following season.

Physical Characteristics


Boxelder bugs have a combination of red and black colors. Their distinct color pattern includes:

  • Dark gray to black body
  • Three red stripes on the thorax
  • Red outlines on leathery parts of wings
  • Red eyes

These red markings make it easy to identify boxelder bugs.


Boxelder bugs have two wings which are categorized into:

  • Leathery wings
  • Membranous wings
Wing Type Appearance
Leathery Dark gray with red outlines
Membranous Transparent

The leathery wings are outlined in red, while the membranous wings allow for easy mobility.

Boxelder Bug Interactions

Nuisance Pest

Boxelder bugs are considered a nuisance pest due to their tendency to congregate around homes and buildings near boxelder trees, ash, and maple plants.

They may enter homes through small openings around windows and doors to seek warmth during the colder months.

Although these insects are not known to bite or cause diseases, some characteristics that contribute to their nuisance status include:

  • Large numbers congregating on the south side of trees and buildings
  • Release of a bad odor when crushed
  • Occasional staining of surfaces due to their excrement


Boxelder bugs have natural predators, which help keep their populations in check. Some of the predators include:

  • Spiders
  • Praying mantises
  • Assassin bugs
  • Birds

These predators consume boxelder bugs, preventing them from becoming an overwhelming problem in many areas.

Relationship with Humans

Despite being a nuisance pest, boxelder bugs are harmless to humans and animals.

They do not transmit diseases or bite, and their main interaction with humans is the annoyance caused by their presence in large numbers around homes and buildings.

Handling boxelder bugs is also safe, but it is important to remember that they release an unpleasant odor when crushed.


Boxelder bugs, commonly associated with boxelder, ash, and maple trees, undergo a life cycle starting with eggs laid in spring and developing into nymphs and adults by summer’s end.

As temperatures drop, they seek warmth, often congregating on building exteriors. While harmless to humans, their large numbers can be bothersome.

Understanding their life cycle, preferred habitats, and seasonal behaviors can aid in effective management and prevention strategies.

Reader Emails

Over the years, our website, has received hundreds of letters and some interesting images asking us about boxelder bugs. Scroll down to have a look at some of them.

Letter 1 – Democrat Bug

Subject: What is this bug?
Location: Dayton Ohio
October 16, 2012 11:46 am
Dayton Ohio….these showed up about a week to 10 days ago and are all over the front of the house when the sun is on it.
Signature: dayton-dave

Democrat Bug

Dear dayton-dave,
Just in time for the 2012 debate season, identification requests for Eastern Boxelder Bugs, or Democrat Bugs,
Boisea trivittata, have been pouring in to our offices.  Most of the photos we have posted lately are of the large aggregations that Eastern Boxelder Bugs form in sunny locations in the autumn, but your photo of an individual Eastern Boxelder Bug is quite exceptional and it will provide our viewers with an easy comparison for identification purposes.  Because of the large aggregations they form, Eastern Boxelder Bugs are frequently called Populist Bugs or Politician Bugs as well as Democrat Bugs.  Swing state voters seem to be especially inundated with Eastern Boxelder Bugs this year.  Though they can become a nuisance when they are plentiful, Eastern Boxelder Bugs are benign creatures that will not harm your home, garden or pets.

Letter 2 – Democrat Bugs

Subject: Eastern Boxelder Bugs
Location: Northeast Alabama
November 11, 2012 4:36 pm
Found these bugs on and around this tree in my yard. thought I would share.
Signature: Samuel

Boxelder Bugs aggregate on a tree trunk

Dear Samuel,
The bark on this tree resembles that of a maple.  Do you know if the tree is a maple?  We also suspect this spot on the bark faces south and it might get late afternoon sun, though there was very flat lighting at the time your photo was taken.  Boxelder Bugs are sometimes called Democrat Bugs, and it would be interesting to see if there is any correlation to the parts of the country where Democrat Bug is used and the party makeup of the inhabitants there.

Democrat Bugs Congregate

Don’t know the type of tree it is. The spot on the bark does face the south.

Boxelder Bugs

Thanks Samuel,
We took a closer look at your third photo, which up until now we had not posted, and some of the leaves on the ground appear to be maple.  Other leaves look like Oak.  To the best of our knowledge, the food source for this species are seeds of boxelder and other maple trees.

Letter 3 – Controlling Boxelder Bugs

Great Treatment for Box Elder Bugs
Hello, I saw a comment on your True Bugs page about laundry detergent (“Soap against Boxelder Bugs”). My family home and yard was once infested with these bugs. I’ve found that both Murphy’s Oil Soap, which is sometimes thought to be good for the veggitation, in a hose sprayer works very well.

Any liquid soap and water mixture will do. Finances forced me to simply use dish soap in the sprayer this season. As long as I get the bugs in their spring and fall hatchings, they are kept well under control! Apparently, the soap removes a coating on their bodies.

They are then left to the forces of nature and will thus perish rather rapidly. On another note, thank you for your service! My 4 year old son and I love to look for different critters on your site! We visit often!
Detroit Area, Michigan

Thanks for the tip Angela.

Letter 4 – Bug of the Month: November 2006 – Boxelder Bug

Bug on House — Please Help Identify
Bugs like the attached are all over my house. They can fly. Please help me identify them.
Thank you!

This is an Eastern Boxelder Bug, Boisea trivittata. We get so many identification requests in the fall that we have decided to make it the bug of the month for November. Boxelder Bugs are True Bugs with incomplete metamorphosis.

The immature nymphs are wingless replicas of the adults, but appear more red as the wings are not covering the coloration on the abdomen. Boxelder Bugs are noteworthy in that they form large aggregations of nymphs and adults, and they seek shelter indoors as the weather cools.

Turn to BugGuide for additional information. We have numerous advertisers who guarantee to exterminate them, but there are also several home remedies that have reported success rates.

Soap against Boxelder Bugs



Letter 5 – Boxelder Bugs: Nymphs and Adults

box elder bugs…
Could you stand another couple of box elder bug pictures? These seem to
have developed a taste for some weeds in the yard…

Hi Pat,
Thanks for the Boxelder Bug Photo. We have decided to give it a permanent place at the top of the True Bugs pages, just above the Soap remedy letter.

Letter 6 – Boxelder Bugs, young and nearly mature nymphs

Any clue?
Hi Bugman!
In desperate need of your assistance. I’ve looked at every image on your site without any luck in identifying these bugs. Attached are a couple of pics. They are located in our backyard in Austin, TX (everywhere you look you see them crawling around. They seem to be located mostly in small piles of dead leaves and on our wooden fence).

Although the two pics look a bit different, I think the “blacker” one is just older because they all “hang out” and run around together. When they are first born, they are all grouped together and start out as a bright red-orange and finally begin mostly black.

I also haven’t seen them fly. I want to guess their size to be 1⁄4” to 1⁄2”. They seem pretty harmless, but my daughter won’t go outside because they freak her out. Not sure if this is enough information, but I will provide any necessary info, if at all possible. Any ideas or help would be greatly appreciated!

Hi Yvette,
You probably only checked out the images on our homepage. If you go to the two True Bug pages by clicking the links in the alphabatized list on the left side of the homepage, you will find lots of great photos and information on Boxelder Bugs. Your photos are fantastic.

Letter 7 – Democrat Bugs

Box Elder Bugs
How did BE bugs also become called Democrat Bugs?
Steve Paige
Topeka, KS

Sadly, Steve, we don’t know the true origin of the common name Democrat Bug. We can only surmise that it has something to do with the aggregations which to some people look like the Democratic National Convention.

Letter 8 – Democrat Bug Aggregation (AKA Boxelder Bugs)

Red and black large group of beetles?
Fri, Oct 24, 2008 at 9:30 PM
As the weather has gotten colder over the past few weeks I started to notice two or three of these guys warming themselves in the sun on my front door. As time went on, more and more showed up, and now as many as 15 or 20 will show up on the front of my house.

A few days ago I was raking leaves in my backyard and came upon this rock with a huge group of them huddled together. Further investigation found other groups of them on other nearby rocks, trees, and piles of dead leaves. What are they?

I live in northern KY, just south of Cincinnati Ohio. They didn’t seem to appear (I didn’t notice them anyway) until the first part of September this year.

Democrat Bug Aggregation
Democrat Bug Aggregation

Hi Kentucky,
These are not beetles. Beetles go through complete metamorphosis so the larvae look nothing like the adult. These are Eastern Boxelder Bugs, Boisea trivittata, and since they have incomplete metamorphosis, the nymphs resemble the adults, but without the wings.

Boxelder Bugs sometimes form large aggregations, and they are often noticed in the fall as cold weather starts to set in because they are known to seek shelter indoors. They will also emerge on warm sunny days in areas with southern exposures.

Though they are associated with boxelder and maple trees, they really don’t do any harm to the trees since the nymphs feed on the juices of the seeds. According to BugGuide, they are also called: “Democrat Bug, Populist Bug, Politician Bug.

Apparently these political terms are primarily used in the Central Plains states as I’ve seen references to such from KAN, NEB, & IOWA. (MQ) .” Though your photo does not show quite as many individuals as those gathering at a Barack Obama rally, they are nonetheless quite numerous.

Your photo is a wonderful example of the great new feature on our website since our recent site migration. By clicking on the small image, you will see a much larger version open in a new window.

Letter 9 – Democrat Bugs

Subject: Wtb?
Location: Lexington, Kentucky, USA
October 13, 2012 2:24 pm
These bugs cover the outside of our house and occasionally get inside, and have infiltrated our screened in porch. They’ve become more prevalent as the weather’s cooled down. We live in central Kentucky. They fly, they’re black and red, about 3/8 inch long.
Signature: Sara

Democrat Bugs

Hi Sara,
You have Eastern Boxelder Bugs, also called Democrat Bugs, especially during election years.

Letter 10 – Democrat Bugs appear on Inauguration Day

Subject: Critters wandering around my house
Location: Washington, DC
January 21, 2013 3:06 pm
We recently moved into a new condo in Washington, DC, and are seeing these little critters (I shan’t say ”bug” until I hear from the bugman!) wandering around. I scoop them onto paper and put them out the window without issue.

I think they’ve been coming in through cracks or unscreened windows left open, though it’s a bit odd that I’m not seeing any other types of visitors.
They seem harmless, but I’d like to know more!
Signature: CreatureWatcher

Eastern Boxelder Bug

Dear CreatureWatcher,
This is an Eastern Boxelder Bug,
Boisea trivittata, a species sometimes called a Democrat Bug because they tend to aggregate in large numbers in sunny locations, a habit that some folks have likened to political gatherings.  Eastern Boxelder Bugs are True Bugs, so you may refer to them as bugs. 

We suspect you are finding them indoors because when the weather cools, Boxelder Bug, like many other True Bugs, seek shelter indoors to hibernate.  When things warm up, they become active and try to find egress to the outdoors again.  It seems very appropriate that these Democrat Bugs made an appearance on Inauguration Day.

Letter 11 – Democrat Bug: Don’t Forget to Vote

Subject: What’s this bug?!
Location: Massachusetts
March 10, 2016 5:56 am
This insect survives all winter and gathers by the hundreds in clusters on the south side of my home, in the sun. They find their way inside my home and I release them. Are they harmful and how can I get them to leave the area without killing them?!
Thank you! Kevin
Signature: Kph

Democrat Bug
Democrat Bug

Dear Kevin,
This is an Eastern Boxelder Bug,
Boisea trivittata, but we are really amused at its other common name, Democrat Bug, so we are postdating your submission to go live the day before the primary elections Tuesday to remind our readers to get out and vote.  Eastern Boxelder Bugs hibernate over the winter, and they will emerge on sunny days exactly as you describe. 

Eastern Boxelder Bugs are benign, though they can become a nuisance when they appear in great numbers, especially if they decide to hibernate indoors.  If you are not troubled with their appearance, you can safely allow them to sun themselves as they pose no threat to you, your pets or your home, nor do they damage plants as they feed primarily on seeds. 

The common name Democrat Bug, as well as names like Populist Bug and Politician Bug, refers to the communal habits of the Boxelder Bugs, and in light of the political circus of the 2016 primary season, we will be featuring your submission for the duration of the election season.

Very helpful, thank you for taking the time to respond.

Letter 12 – Democrat Bug Nymphs

Subject: Red beetle
Location: Shenandoah Valley, Virginia
June 14, 2016 7:52 am
I think these are the babies of a black and red beetle. They have swarmed my echinacea!
Thanks for helping to identify.
Signature: Kristen

Democrat Bugs
Democrat Bugs

Dear Kristen,
These are immature Eastern Boxelder Bug nymphs, not beetles.  They are sometimes called Democrat Bugs because they aggregate in large numbers.


  • Bugman

    Bugman aka Daniel Marlos has been identifying bugs since 1999. is his passion project and it has helped millions of readers identify the bug that has been bugging them for over two decades. You can reach out to him through our Contact Page.

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    Piyushi is a nature lover, blogger and traveler at heart. She lives in beautiful Canada with her family. Piyushi is an animal lover and loves to write about all creatures.

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