You can prevent ants, flies and other insects from entering your home by applying a long lasting residual product such as Talstar. Talstar kills over 75 different insects and is safe to use indoors and outdoors, is gentle on plants, is odorless, dries clear, leaves no stains, is non-irritating to the skin, and won't break down easily with rainfall. We also suggest you use Integrated Pest Management or IPM. IPM is a step by step approach that helps you identify the pest and determine why that pest is there, and then determine how to exclude the pest in the future. Please read the IPM article to learn how to successfully stop pests before they become a problem.
If you are indeed dealing with boxelder bugs, and what you have described does sound like boxelder bugs, then a product called Talstar P will do a great job for you. Talstar P can be sprayed directly on the plant foliage and it can be used on and in the house. We do recommend that you look up a few pictures of boxelder bugs online just to be sure they match the insect that you have spotted at your home.