New answers tagged ants
As keshlam mentioned, always start with pressure treated lumber. Beyond that keep it sealed/stained every year, it doesn't sound like you will have much wood left once you replace with the composite so it should be pretty easy. This helps prevent rot and splitting and can keep insects away. It will also help prevent things growing in and on the wood.
Pressure-treated lumber, or one of the tropical hardwoods which develops its own insecticides, should be proof against both termites and carpenter ants for many years. Outside of that, catch and fix rot early, since carpenter ants are most likely to move into wood that has already suffered some damage.
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