Tons of wasps and bees drink at my ponds. I am allergic to their stings but I don't let them bother me. They have never been aggressive towards me near the ponds. I have thousands of bees in the yard. I do try to stay away from yellow jacket hornets as they are aggressive.

Well, to be honest, I don't know if they are yellow jackets, but I don't want to find out. I can probably try to take some photos, and post them. Often, several are crawling around, either drinking, or eating algae. As for watching them at dusk, I have tried, and I have no idea where they are going. They just seem to all of a sudden disappear.

Yellow jackets are yellow and have one main segment. They look like bees except that bees have a more golden color. Yellow jackets do live in the ground and could be living right there, especially if there is a BBQ near by, or dead frogs, fish etc. Many wasps have a second segment, are slimmer and tend to bumble around and are not agressive at all. I would think you could google any of them for an idea of what what you have.

If you have not seen them flying into the ground, they probably don't have a nest right there. You might want to look closer because if they do have a nest, it is actually easy to kill them by pouring somewhat dilute malithion, or whatever, right down their hole after dusk. Your liner would prevent the poison getting into the pond unless they were very unlikely nesting in an island of some sort.

The liner comes up under the perimeter of rocks, so I could not treat anywhere with anything toxic.

Okay. The camera sees what the eye does not. Not wasps, but yellow jackets, and after sitting and watching for over an hour, it looks as though they all went into their nest, situated under the rocks on the perimeter. Now, I have to figure out how to get rid of them without having someone dig up one whole side of my pond - at night!

I have an electric fogger that I've used around the pond - to date no problem. Can you put a sheet of plastic, used for drop cloth for painting, over that area of the pond at night and then fog them while under the plastic ??
Or use a bait trap under the plastic, making the plastic like a small tent with the bait trap under the plastic

I have a few bait traps set out, and nothing has even entered them. Putting plastic over the area is not necessarily going to work, because the area is not flat. There are large stones, pebbles, plantings, etc. What I did try last night, which of course did not work, was to take a very large glass bowl, tape bubble wrap on the rim in order to possibly get the uneven areas on the rocks sealed, when the bowl was placed over where I think they were entering. This morning, there was perhaps one yellow jacket inside the bowl, and plenty of others enjoying the perimeter of the pond. Of course, there may be a lot of nests, as well. I do note that they spend all there time on the side of the pond which is somewhat lower, and where the rocks are always wet, from water lapping onto them, and where some algae does accumulate. The opposite side of the pond, which is totally dry, has no activity. When you say "fogger", I am not sure what you mean. I have foggers in fountains, in the house, but I don't see what you are suggesting. I have just added some tadpoles to the pond. It occurred to me that I had frogs for a few years, and had no insects at all, and then the frogs disappeared. I am worried about people being stung, my dog, to boot, and having to avoid the yard all Spring and Summer. I have photos of the little buggers, but am not sure how to post them here.

I am sorry. You appear to have a very difficult problem. First, yellow jackets are very agressive when the nest is disturbed. fortunately, they generally don't otherwise attack people, but they do persue those with fat laden food and when you or guests have a hot dog or piece of chicken, you will have them flying around your face and open mouth and a sting anywhere really hurts.

There are specific yellow jacket traps. Perhaps yours weren't the right kind? They are large yellow containers with an internal bait and the yellow jackets can fly in but can't fly back out. I don't know if these traps will remove the nest. Since the trap actually attracts them, it could actually bring more. However I just read that this IS the right time to trap them because the main flying yj are the queens.

I think google is your friend here and can give you some more ideas. However, I suspect that your best and most unpleasant approach is to disturb/distroy the nest mechanically. At dusk you dress in a home made bee keepers suit that you have checked to remain sealed with serious movement, and then as night descends, quickly remove the rocks and with shovel and rake get to the nest and if lucky, shovel it away and spray it with a can of poison. And then run like hell.

Don't eat or drink anything near the pond until you get a handle on your problem. Soft drink cans are especially dangerous.

Check out some of the info from the Co-operative Extension services for good advice. Yellow jackets can get very nasty when flowers are in bloom.

Good luck.

Here is a link that might be useful: Co-op Extension papers on yellow jackets

I probably will not be eating out in the yard, so no problem. FInding, and dismantling, the nest would be a major job. Just because I see them crawling under the rocks at a certain point does not mean the nest is right at that point. I would have to take away everything on that side of the pond to even look. I'm not even sure, if i get that far, I would even find it.

The fogger: is an electric machine that vaporizes a liquid insecticide that is poured into a container on the fogger - the plastic: the idea was to cover the entire area and form a tent that would contain the fog - the plasti around where the bees are. The rop cloths at Walmart, etc. are about 10' square so that gives quite an area of coverage, even if you just capture/contain the bees they will die or maybe cover the area so that they cannot return will drive them to another location - just a thought

"Just because I see them crawling under the rocks at a certain point does not mean the nest is right at that point."

GENERALLY speaking, it does mean exactly that. Admittedly, your situation is unusual because there is a liner presumably just under the rocks and a little dirt. I don't know what yellow Jackets would do under those circumstances. I would have assumed that they wouldn't build a nest at all. However they seem to be there. Of course the entrance could be very near the liner edge and the hole could be a normal one 2 inches deep just outside the liner.

I once had a nest of yellow jackets under a cedar stump that I use for a "table". After they chased me into the house a time or two, I used a spray and killed them out, even tho I hated to do it as they are important pollinators. When I tipped over the stump, I dug out the nest. It looked exactly like a hornets' nest, only it was underground. They must have built in a void under the rocks, and it might not be easy to get them out. It is unusual for them to return every year as they usually only build annual nests.

Try some of the ideas in this link:

Here is a link that might be useful: eradicating yellow jackets

I have the same problem well move a rock sometimes there is a little hole in mulch.Its a small kinda yellow jacket,My jack russell got in flower bed last year and they got her ,stung her like 10 times,we either watch see where they go in and get gardenhose and fill the hole, wait till just before dark spray bee killer in hole cover up.That usually takes care of them.We have this problem every year,I have 2 jacks,4 grandkids.

If I could post a photo, you would see the problem. There are a bunch of really large, heavy rocks, and a lot of smaller rocks and gravel. Move one rock, you need to move about four or five. I wouldn't even know where to start, and I would have to do it after dark, to boot.