We just battled this all spring, summer and fall. They got horribly worse this past September when I finally took action and started searching for an answer to them. They are boxelder bugs and love the boxelder tree a member of the maple tree family. They come every spring and fall if you don't get rid of them. When it gets cold they will try to find a way in your home. They are harmless but annoying. They multiply like crazy! Hubby went to Lowes and bought this http://www.lowes.com/pd_188467-316-1666017_4294772324__?productId=3186209&Ns=p_product_qty_sales_dollar|1&pl=1¤tURL=%3FNs%3Dp_product_qty_sales_dollar%7C1&facetInfo=. It attaches to your water hose and he gave a good spray all over the house, yard, tree, deck, you name it. It totally reduced their numbers greatly. The following weekend he used another bottle of it and did it again. Gone. I haven't seen any outside since. This stuff really works! Hope this helps you.