An infestation of spiders, ants and beetles coming into your home during the winter months could be traced back to one source: firewood. Keeping firewood stacked up or in a basket by your indoor fireplace could be the source. With warmer temperatures inside your home, nesting insects inside the wood become active and flourish. Even keeping firewood by your front door could be a problem -- all insects need is a small crack to enter. Rule of thumb: Keep firewood at least 30 feet away from your home and covered with a tarp.