The answer to 'when to treat for spider' is that the best time to treat for spiders is in the fall, before they start moving indoors to find shelter for the winter. Spiders are most active and visible during the autumn months, so this is the ideal time to apply pesticides or use other control methods to eliminate them from your home.
Treating for spiders in the fall is effective because it targets them before they have a chance to lay eggs or establish large populations inside your home. By addressing the problem proactively, you can prevent spiders from becoming an ongoing issue throughout the colder months.