probably young boxelder bugs - they get darker when they are mature and they look black and red, but the young ones look mostly red like these. They don't cause any harm really, but they tend to come out in swarms. We have had them before around the base of our porch and they kind of freaked me out at first. You don't need to exterminate or anything. If it's getting cooler where you are they may be swarming trying to find warmth. Sometimes they'll get into your house through cracks or whatever they can find - suck them up with the vacuum if they get in - otherwise if your house is sealed tight, they'll move along looking for another warm spot.