What’s Bugging You? Box Elder Bugs

Box Elder Bugs - Boisea trivittata (A.K.A Manitoba Maple Bugs)

Box Elder Bugs are primarily a nuisance insect that congregate in a mass on the sunny side of buildings and trees in the fall.  They are quite an annoyance as they gravitate toward the warmth of house siding, foundations, around windows and in wall and door cracks looking for a winter home.  They are ½ inch in length, oval and black with red markings and a red abdomen.    Infestations usually happen in five to ten year cycles and only if the previous summer has been hot and dry.  In cooler areas they will winter over in a dormant state. 

The good news is is that they are not harmful to humans or pets and do not carry disease. If they happen to enter your home they will only live for a few days to a week.  They will not reproduce or attack your houseplants.  However, box elder bug excrement will stain curtains, furniture, and clothing.  If squashed, they emit a foul odor that attracts other box elder bugs to their location.

Box Elder bugs have two generations per spring/summer season.  In spring, the adults emerge from their winter home and fly to the dropped leaves of a female Box Elder tree. There they will deposit their oval red eggs on the seeds.  The first- generation nymphs are bright red and stick together for warmth.  They will feed on the box elder maple seeds, nearby plants and even fellow nymphs that are in the process of molting.  Predators avoid them due to their foul taste. 

The nymphs become adults in early summer and continue to feed on the sap of the Box Elder’s flowers, leaves and seeds.  Surprisingly, they do little damage to the tree itself.  In late summer the second - generation eggs are laid on the Box Elder seeds. The nymphs will stay on these seeds, eating and developing into adults well into October if there are no hard frosts.   Once the first fall frosts arrive, it is then that they will seek out warmer shelter.    

So what can you do about these pesky critters that are gathering, sometime in the thousands, on the outside walls of your home?

- Seal cracks in foundations, windows and doors.  Fix loose siding.

- Put a few inches of water in a shop vac and vacuum them off the exterior walls, doors and windows. They will drown inside the shop vac.  Put them in a sealed bag and into the garbage.  

- Wash them off the building with a high-pressure water blast from a hose.  Better yet, mix liquid dish detergent and water and spray them with the mix.  Some will fly away, some will die and the cleaning solution will repel other box elder bugs.

- If Box Elder bugs have become a major fall problem in your life and you have a female Box Elder (Manitoba Maple) in your yard, consider getting rid of the female Manitoba Maple and planting a new male one. Female Box Elder trees produce seeds called samaras. Male Box Elders do not produce seeds!

Do you have a picture or story to share about Box Elder Bugs? Share it with us in the comments below! 


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