Box elder bugs (Leptocoris Trivittatus) is a common bug named for the tree they love: the Box elder maple.
They feed on this tree and others, but they become an annoying household pest in the fall as they scurry and swarm to find winter shelter.
You will find them clustering on the siding of your house, typically on the south side. Other hibernating places they might find would be behind loose bark of tree gaps, in window sills, loose siding and anywhere else they can crawl into.
BOX ELDER BUG CONTROL
A contact insecticide like Zeps 'Bug Max' will work effectively; as well as Bonide's Beetle Killer that hooks up to your hose. Always make sure you test spray a small are to make sure the product you are spraying does not stain your stucco or siding.
Employ a building maintenance plan. Seal up cracks with a good silicone sealer. Reattach any loose siding; replace bent window sills and screens. Make sure exterior doors close tightly and inspect all weather stripping. This will stop them actually penetrating your home.
Earth friendly options are also available, one being 'Eco Smart' organic insect killer. It kills and repels over 100 different insects and bugs including Boxelder beetle. Although it's labeled non-staining as with all products, spray an inconspicuous test area of siding and wait two hours to test it out first. If you don't notice any changes in siding appearance you can go ahead and spray. Another product that is eco-friendly would be Bonide Eight.