There are commercial products that can be sprayed which are both environmentally sound and non-toxic to humans, I think they are a repellant more than an insecticide. Years ago we had our boat sprayed several times and it was quite effective and affordable. A club member would organize several of us and schedule a time for the application. Sorry, I don't know the name of the product.Anyone have any experience using a commercial insecticide and spraying everywhere? Full treatment.. all interior and exterior. I dont see why it wouldnt be as much if not more effective than residential use. Its a smaller area and easier to treat than a home.
A key to the success of any method is starting at the beginning of the season before the spiders start laying eggs. Once the eggs hatch the population explodes and it is nigh unto impossible to control the numbers.