I noticed a large Spider the long leg ones next to my Seedlings inside my room, should I take it out or leave it, I do have a small fruit fly problem in my seedlings, but could the spider be a bigger problem?
Spider might help...but it's probably not fruit flies. If it's localized around your seedlings it's probably fungus gnats (which I recently learned are totally different from fruit flies). Let your soil dry out good before the next watering and it'll take care of the fungus gnats. After that the spider's fate is in your hands. I'd say place him outside in the garden. Spiders are a welcome visitor in my garden!!!!
No you can't let the soil dry out totally and that is why fungus gnats are such a problem with indoor seed starting. But do be very careful with water and type fungus gnats in to Search the Forum keyword box and find tons written here about them. One thing that really helps is increased air circulation, like a small personal fan.