Yes, Eco PCO WP-X is labeled to treat for Granary Weevils. Mix 1 water soluble pouch per gallon of water and apply at a rate of 1 gallon diluted solution per 1,000 sq ft of surface area. Please refer to the product label for full instructions.
Eco PCO WP-X is not a contact kill product. The time frame it takes Eco PCO WP-X to eliminate spiders will depend on the number of spiders in the area and the other insects (their food source) in the area. It could take up to a week to see results. This product does not guarantee that the spiders will be gone forever. The product will likely need to be reapplied for maintenance every 30 days.