The best way to get rid of black widow spiders is to eliminate their possible habitats. Remove woodpiles and lumber piles or at least keep them away from children and pets. Clean and vacuum houses, garages and sheds regularly to clear out webs, eggs and spiders. If you come across an individual black widow, you can carefully spray it with aerosol pesticide. Be careful not to attempt to kill it by simply hitting it because they can because aggressive if threatened. If at any time you feel that the problem is becoming a larger issue, contact a local exterminator to take care of the infestation.