I keep getting wasp that appear to be trying to nest inside my mast (enter through the internal haylard holes), and also try to nest under the mainsail cover while sitting at dock.
What is best repellant to use? If I spray with wasp spray will it damage my haylards, paint, sails, or fiberglass.
For wasps to be so common on your boat ...... and such 'mud daubers' REQUIRE the living carcasses of SPIDERS to grow their 'young' ... remove or kill any and all excess spiders you find in your area.
There are 'spider repellents' available to help keep the spider population in check: http://www.amazon.com/Star-brite-Spider-Natural-Repellent/dp/B001R1AQ5U You can also do a websearch for DIY 'spider repellents' and use them on the adjacent areas where you keep your boat.
The less/least population of spiders the less/least population of 'mud dauber' wasps. Mud daubers require a large population of spiders to feed upon and to lay their egg in.