There are a few spots in siding where you can successfully introduce insecticides.
How to seal siding from bugs.
Caulk is cheap easy to apply and can go a long way towards keeping bugs out.
Seal small cracks and gaps in your siding under 1 4 inch wide using an acrylic latex caulk.
I d use dusts but the ready made hole is far to small.
Use caulk to patch small cracks in foundations and siding or use it to seal joints where the siding meets the roof or foundation.
Add caulk around window frames as well as around any air intake or exhaust grilles.
And unless you want to cover the wood with epoxy to completely seal everything in i don t think there s an impervious finish against insects.
Paint works well over it.
I take advantage of these tiny holes using pyrethrin aerosols and an injection straw.