Black locust borers-Fence posts

[Faron]

I am looking at a bunch of small black locust trees, some that would make line fence posts.  Most are damaged by what I think are black locust borers.  Anyone know how the insect damage will affect the durability of the wood for posts?  How deep in the wood do the tunnels go?  I will get some pictures next time I am over there.  It is interesting to see the kind of grass around these trees, due to the nitrogen fixing properties of the locusts. 

edit:  Aw shoot, I intended to put this in Forestry and Logging.  Admins., can you move it for me?

[rpg52]

I can't answer from experience unfortunately, have only used a bit of Black Locust - however, I wouldn't think some holes in it would substantially reduce the life time of a locust post.  It is rot resistant because of the chemical make up of the heart wood.  (Sapwood will rot anyway).  Holes might reduce the lifetime a bit (only 50 years instead of 70?), but you probably won't live long enough to see your posts rot off.  I pulled apart a pile of locust logs, dirt and junk one time.  After sitting in a pile for ~10-15 years, the sapwood was gone, the junk was rusted but the locust heartwood was good as new.  I don't think you have anything to worry about, IMHO.   
Ray

[Ironwood]

Bark borers (likely what you are talking about) can and sometimes do hit heartwood. They are VERY common around here in SW PA. I'd still use them, it would be likely 60% of my local trees would be effected.

    Ironwood

[Mr Mom]

I was thinking of using railroad ties and they will last longer than you.

Thanks Alot Mr Mom

[Faron]

Thanks, everybody. I think if my project goes through I will use them.  I am working on a deal that may require miles of fence and thousands of posts.  There are a great many black locusts growing on the property, maybe enough to supply at least the line posts.  I may be able to buy loads of new 6 x 8 ties for corner posts. Don't know the costs, yet though.