how can I treat mud daubers that are nesting in outboard boat motor?

I am looking for something that I can put under my outboard boat motor tarp cover that will keep out mud daubers. I am not trying to kill all of them just trying to keep them out of my boat motor. They can ruin a motor. Thank you for any help.

I keep an I/O under a covered dock that has this exact problem. The daubers love going through the vent holes and nesting inside my motor compartment. I first tried installing some PEST STRIPS which no doubt stopped them. But because the boat is kept open with no cover on it, the strips evaporated too quick. Inside of 2 weeks they were gone. Since your boat is covered with a tarp, I would think the strips would last longer and if you got 1 month or more of protection from them, this would prove to be an efficient way to stop them. The Pest Strips release slowly and insects don't like the scent so they'll stay away where the odor is present. Wasps and bees are particularly sensitive to it so they won't linger therefore they you won't be killing them.

Since the strips didn't work for me, I went to an aerosol called PHANTOM. It's odorless, goes on dry (which was very important because I didn't want to mark up my boat deck) and treatments seem to last about 3-4 weeks. The Phantom stopped the wasps as well as the spider problem I have. But it will kill them so I don't think you'll want to use this option.

For nothing but repelling pests like wasps, another option would be the NBS. It's a liquid that can be used as a paint or stain additive but can also be used as a spray. Just mix it with water and spray down the motor housing. Is there a chance it will discolor the housing? Sure. I say this just to insure you try treating a test spot first before you treat the entire housing. We've been selling this product for years with people applying it to their homes and during this time we've not had one complaint of it affecting the paint or any other finish they've treated. But I can't say I know of anyone using it on an outboard motor housing which is why I suggest testing it first.

A third option would be to set up an AEROSOL MACHINE with some KONK in it. If you place this machine up under the tarp and program it to release every 15 minutes, I'm sure it will deter and not kill them. Konk contains Pyrethrin and is an excellent repellent. Unfortunately it doesn't last which is why you need the machine. The machine is easy to deploy and can be programmed to work around the clock. And a can can last 30-60 days so it's cost effective. I'm sure because you'd be using it up under a tarp the release of pyrethrin could be directed where the wasps want to nest so they'll have no choice but to leave and stay away.

Here are direct links to the information and products listed above:

Pest Strips:  http://www.bugspraycart.com/repellents/fumigant/hotshot-no-pest-strip

Phantom:  http://www.bugspraycart.com/insecticide/aerosol/pt-phantom-17-5oz

NBS:  http://www.bugspraycart.com/exempt/additive/nbs-paint-additive-16-oz

Aerosol Machine:  http://www.bugspraycart.com/equipment/foggers/aerosol-dispenser-2000

Konk:  http://www.bugspraycart.com/insecticide/aerosol/konk-974-py-6-5-oz