reisjdmd, good question. I once used the same corrugated tubing around my trees, but it caused more damage placing and removing it than it may have stopped, so I finally left it off. As I'd carefully slide it over the trunk it would inevitably pinch tight and cut into the bark - not good! Another thing I found were occasional ant nests! It made sense - dark, warm, all those little 'shelves.' And they could scavenge in the trees or grass for food. I assume you've got the same 'small' ants as I had? If they were Carpenter ants I might be more concerned... And there are also those 'medium sized' ants… but they seem to protect and spread aphids, and I've never noticed them 'chew' on the bark or leaves.

My suggestion would be to paint the trunks with a white latex interior paint (pick your gloss). That's what I eventually did. I then ringed the trunk with an inch wide smear of Tanglefoot (ultra sticky stuff) to stop anything (generally ants) from climbing into the trees. My only problem were the steel posts I'd use for fencing the trees during their early years; things would climb those posts - then into the trees wherever they touched the fencing... But at 7 feet high yours are well out of the reach of deer, if not elk... I've had buck deer shread some trunks... but placed re-bar 'tomatoes cages' around those - and got a bigger dog " title="Wink" />

So I think you've simply discovered ant nests, but unfortunately, ants don't seem good for anything other than bird food

Interior latex paint lacks a substance that's harmful to the trees, but I can't remember what that substance is? But white interior lasts just fine, and reflects sun - so the trunks aren't scalded while young, and it stops or slows down chewing insects like Borers. You can more easily see ants trekking up (empty) and down (swollen with aphid nectar) while it makes a good surface to apply Tanglefoot. I also like the looks, and a few of my white trunks may have saved them from being backed into or hit by the riding mower, or weedeater… And that suggestion was more an alternative to the corrugated tubing; I don't know if anything enjoys the taste of latex paint.

I also made that "longitudinal slit" in my tubing, but the brittle plastic tubes I used would pinch tight and occasionally scrape the bark no matter how 'carefully' I’d remove / replace it... So I stopped replacing it! It did protect the trees well from danger outside the tube, but maybe it was the mouse nest I found (along with snakes, ants, earwigs, and 'potato bugs') that finally convinced me to take off the tubes? Also, the bark would look a bit strange (as if it hadn’t seen sunlight), and would develop small 'bumps' as if it were trying to root. Anyway, I have several young trees right now but wouldn't mess with the corrugated tubing.

I've seen it suggested, and used around the trunks of Fuzzy Kiwi plants - to reflect the late winter sun and keep the sap from flowing too soon. I held off using it there too, but have had a real problem with Sapsucker (woodpeckers) birds riddling the kiwi's bark. I considered the corrugated tubing... then reconsidered and placed chicken wire (poultry netting) around both the male and female trunks - no problems. So you can also use loosely wrapped 'poultry netting' around your trees (I'm doing this too in another location for Beaver - throw in our bear and it's a wild kingdom out here!). I'd reconsider what you're protecting the trees against, and go from there.

I think you're safe with the smaller ants, as far as their eating the bark; they were most likely using the tube as a nest. I don't think Carpenter ants will eat live wood... but then I'm still learning about their ways. I suspect the small ants will go after the fruit, but not in numbers sufficient to threaten the crop. There are usually a hundred tiny ants feeding on one bird-pecked cherry. They'll go out of their way for figs though, and the way I allow multiple trunks with my figs I can't defend the trees, or clumps; but here again, they're usually content with one or two fruit. But if you've stand-alone trees with Tanglefoot around their trunks, the ants are excluded.

I left the corrugated tubing on my trees year round; where there was enough space above to the first set of branches I'd occasionally 'slide it up' to see what was going on under there. …You never knew what might dive out! If I were to use it again I don't think I'd 'force' the tree to 'grow it off.' I'd start at the top and cut down the opposite side of that slit, leaving 'two buns halves' – and ruining the tubing for future use… but saving that bark-scratching damage I'd described. Perhaps your question about the 'bark maturing' may be the answer to my description of the strange 'otherworldly' look of the bark under that plastic. But if you took it off now (summer time) it would likely be very susceptible to sunscald due to the fact it doesn't know what sun is? But if you were to paint it ...Sun screen

PS; sorry for my long posts, but I use them as a ‘teaching opportunity’ and try to include a bit more info so as to appeal to more than just the person asking the question.