Mechanically remove spiders and mud-dauber wasps with a long-handled brush. Make sure that you remove the egg sacks and nests regularly. They will continue to hatch out from past unremoved egg sacks however continued vigilance will demonstrate fewer spiders and webs over time.

Use essential oils to deter pests from getting established on your dock. These oils have a strong scent that interferes with how insects navigate and communicate with each other. It repels spiders, wasps, hornets, boxelders, Asian Beetles, and several other nuisance insects.

Fill a spray bottle with water and 15 drops of essential oil (peppermint, cedarwood, tea tree, vetiver, orange, cinnamon). 

Spray your dock, especially where spiders might build a web.

If these methods aren’t producing the desired results, you may choose to call a professional.