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.
Talstar P (Talstar One) will only kill those bugs that contact a treated area and states on the product label it should not be used alone for effective eliminate of bed bugs. This residual can last up to 90 days inside along baseboard, cracks and crevices, etc. It will not prevent a reinfestation. Typically, one product will not do the job. That's why we offer our Bed Bug Kits which have multiple products that are used in different areas in the bedroom and that do different things. The kit is exactly the products that a professional company would use and charge you hundreds of dollars to apply. All of our kits come with full instructions on where to apply each product. We make it easy as possible for you to treat your own bed bug problem, and our kits have a very high success rate when used correctly.
We also have a helpful prevention guide here.
Talstar P Professional Insecticide is a water-based chemical and will not cause corrosion to stainless steel or galvanized metal. Keep in mind that you should not apply this product directly to food, feed, water, or sources for food or water. You also cannot apply this in a way that would contact the animals or their food or water. Keep in mind that a good fly control program includes the use of multiple control measures such as baits and traps, in addition to insecticides.
The rate for Talstar P in a hose end sprayer would be the same as if you were using in a pump sprayer, 0.5 to 1 fl oz (1 - 2 tbsp) per gallon of water for low volume applications, or 0.5 -1.0 fl. oz. per 1,000 square feet in a higher volume of water.