Appearance

• If you were to see a boxelder bug and milkweed bug from a few feet away, they would be nearly indistinguishable. However, close inspection will reveal small but significant differences between the two insects. Both of these bugs grow to be about ½ inch long, but the milkweed is a little wider in the middle and features a wider head. Both bugs are black with orange or yellow markings. Milkweed markings are wider than boxelder markings, covering most of their wings; the majority of the wing and body area of the boxelder is black.
  
  

Habits

• The easiest way to identify these bugs is based on where you find them. Both of these insects feed solely on their namesakes: boxelder bugs on boxelder trees and milkweed bugs on milkweed plants. Neither insect does much damage to the plants; each bug only eats a little of each plant. However, large infestations are extremely detrimental to the look of the tree or milkweed, and can cause serious damage if all of the bugs feed and lay eggs at the same time. The bugs cause no potential threat to humans.
  
  

Indoor Issues

• The biggest nuisance caused by the boxelder and milkweed bugs stems from their migratory tendencies. As colder weather sets in during the fall and winter, adult boxelder and milkweed bugs naturally leave their trees and plants and migrate anywhere they can find warmth. This generally leads them into sheds and houses, where they become nuisances inside. They can get in under doors and windows, as well as in any cracks or crevices within the foundation or walls of your home. If you experience a warm winter day, you will often find them lining your siding to soak up the sun and warm air. They will leave again in the spring to lay their eggs on their respective plants.
  
  

Control

• Because these bugs cause little damage, there is rarely a need to treat them. However, if they become a major nuisance in your landscape or home, there are some steps you can take. Most generic insecticides will kill or drive away boxelders and milkweeds. You can also vacuum up the insects and dispose of them outdoors again. The only way to ensure that you will not have a problem with these insects is to remove all female boxelder trees and all milkweed plants from your landscape.