Need help identifying a suspected pest house spider
I've encountered this spider in our house on two occasions since spring. Unfortunately, on these occasions I needed to destroy it real quick, for its appearance in the house and behaviour seemed suspect to me. Now I need to better inform myself before the next killing (...or before being bitten to death!), but I hardly know where to look...
Best I can do is try and describe it. A 3/4 in. long jet black spider with a few white markings on the back. Somehow elongated in shape. Legs not very long. Now this unfamiliar appearance aside, what struck me as "alien" was the EXTREME SWIFTNESS with which it crawled (it didn't jump, at least on those occasions where I saw it)! I am very familiar with common brown garden spiders (the ones with the tough, sticky webs that cling on you) and of course house spiders, and this moving speed was really something else!
Each time we observed it, it was in broad daylight.
Come to think of it, the number of regular garden spiders here seemed to have diminished a bit radically; I hope this is just a coincidence!
Sorry if this isn't really the forum to ask about this. If so, where to go?