Aluminum foil sounds good, but could be a lot of wrapping. It sure sounds like moles, voles, or ground squirrels. Do you have a cat? Try feeding it in the orchard for a while so it hangs around there--it might take care of the problem. Another thought is to put out rodent baits in the orchard. Cover them with a big butter dish or something that way with a few holes cut in the sides and partially buried in the ground to hold the containers in place, upside down (no lid). The rodents will be able to get in to the bait, neighborhood cats and dogs won't.

I have had raccoons eat my drip tubing on occasion but not regularly. I could tell by the teeth marks that it was raccoons. My drip system is on at night when the coons are active. I just patch it up, if it was a regular problem I would be forced to rethink the system. Al

Thanks to all for the thoughts. I found a few more breaks today, and in one case, the animal bit off the relief valve and dumped it (and its stake) six feet away. The valve was dented and chewed up pretty good, with deep puncture marks from the molars. It looked (to me) like raccoon or coyote. Since the system was undisturbed all year before being eaten in a dozen places one night, I'm assuming that I'm dealing with an itinerant pack of nocturnal animals.

It wouldn't be too bad to wrap with foil duct tape. We've lost several cats to coyotes in the yard, so I'm afraid they would function as a decoy rather than as a deterrant, and the effect would be short-lived. Problem is, the coyotes might prefer the foil. We had a dog that loved to eat aluminum cans.

Since the foil is conductive, and since the water is grounded, maybe I could put an electric fence charger (or starter coil) in line. Hmmm, crispy critters...

Now that is creative thinking Mattdog! If it's coyotes, they'll learn real fast.

If they are after the water, you could always put water out for them.

I'm always worried that placing water out will simply attract more pests into the neighborhood. Still, I have water out to attract quail and hope it doesn't bring in too much that I don't want to have.

My drip lines squeak when the water is running. If it is coyotes, they might be trying to locate what is squeaking. They are very curious animals.

I've got coyotes fenced out of my orchard, so that is an option if it is coyotes doing the damage. Raccoons are a lot harder to fence out.

That's a good thought, but our in-ground swimming pool is 20 feet away, so I doubt that they're after water. It's more likely that they seek entertainment. Or maybe the pups were teething. And yes, there seems to be a major ecosystem centered around that pool.

My drip lines do squeak on startup, and we did hear the neighborhood coyotes howling nearby last week, so it's possible that our local doggies were chasing the noise. That would certainly account for their digging up the buried line. But the damaged lines are on three different valves that are activated 30 and 60 minutes apart, and the start time for the first is at 8AM. The coyotes don't usually hang around very long. On the other hand, we've watched a family of raccoons play with the pool toys for hours. We've also had skunks and possums visit. All are generally long gone by broad daylight. I'd never heard that any of them go after drip lines, so your information is most helpful.

This is by no means the worst thing that's happened to this orchard, but it may be the strangest. Again, many thanks for your responses.