What are these tiny red and black bugs crawling all over my house?

Question: I live in Kansas City, and whenever it gets warm this winter, I have these tiny red/black bugs crawling all over my house, and they smear red when you touch them. They don’t seem to do any damage, but they are starting to show up inside now. I have had them sprayed before, but they seem to keep coming back every time it gets warm out.

Answer: Probably what you have found are box elder bugs (Boisea trivittata). There are few other insects that have this coloration. The milkweed bug is similar, but they are found on flowers and not on trees, and they have orange markings. Box elder bugs are red and black.

Box elder bugs are plant feeding insects that usually utilize the seeds of box elder or maple trees for food.

They generally prefer to be on the female (seed-bearing) trees, and are there in the spring when the leaves and seeds begin to form. Box elder bugs have been reported on oak trees and some other tree species, and may use these trees when there are few box elders in the area.

These insects have 2 to 3 generations per year. The fall generation overwinters in protected places. This sometimes includes sites around and in houses, which makes them a nuisance. They have some chemicals (called pheromones) that help them to gather in large numbers, so oftentimes thousands of them will gather in one place to spend the winter.

Outside: It is best to start looking for points of entry around your home. Make sure window and doors are properly sealed, screens are in a good state of repair and so on. Focus on keeping the bugs out and not letting them gain entry into your home.

Inside: Unfortunately some may gain entry into your home. They can be removed from inside the house with a vacuum cleaner. You may have to keep doing this for several days to get them all. During the winter they can be active during warm and sunny days. They don’t bite or sting or reproduce inside of houses, but if crushed they could stain fabric.

For additional treatments, contact your local Orkin Branch Office.

A highly trained Orkin Pest Specialist will come to your home, assess the situation and develop a solution, backed by science, that best meets your needs.

Related Questions: Orkin used the information above to also answer the following questions submitted by Orkin.com users:

Question: We are being invaded by black beetle like insects with an orange-red marking on their backs. Can you help me identify them?

Question: Hello, I live in southeast Michigan, and I found a common beetle, but I do not know what it is. Can you tell me? It has a long, black back with a vivid red-orange outline and two red-orange V-shapes on its back, if it were facing you. It has long antennae and red eyes. I usually find it on my front porch or on a window. Thanks for your help.

Question: I keep seeing these big flies that have orange tips on the front where the eyes are and an orange tip on the bottom. The wings look grayish in color. I mostly see them around the window sills, kitchen or bathroom. When I spray or swat at them they fall to the ground but do not die unless you smush them. I thought they were drain flies, but now I’m not sure—they’re bigger than the average fly and make a really loud noise when flying. Can you tell me what type of fly it is and what would get rid of them? I just started seeing them in the house. The windows and doors are never left open, so I do not know how they got in.