What slimy_okra said except let me add to it. Water or soap or neem oil will take care of them but you have to be diligent. Spray them off with a water nozzle a couple times a day about 3 days apart for a week or 2. Then, soap the next week about 3 days apart for one week and once every 2 weeks thereafter if the water didn't reduce the populations sufficiently. Funny slimy mentioned cabbage worms -- I don't see any indication either. In fact, I've noticed through the years that(compared to other brassicas) the caterpillars don't attack KALE as much. And Yes... BT for all my Moth(caterpillar) needs. Good stuff. Kevin

maybe it's bad manners to answer your own post, but I guess I just didn't give my question enough careful thought. I got to thinking that if this is indeed a beetle larva, and given that there are so many of these dang holes, it seemed logical to assume that I must surely see hordes of the adults around at some point. So I sat and thought about the insects most common to me from this creek. Some of the more familiar candidates were easily ruled out. I then crossed off the diving beetles amd similar aquatic possibilities because most of their larval stages were totally water-loving, not high and dry like the mystery suspects. Then I thought of the tiger beetles! THere are HORDES of tiger beetles in this creek.... I flipped through the field guides and there it was, a pretty close description of my subject,complete with a tunneling habit, stout jaws, and even the hooks on the back--my "hinge"--- although I had to go back on-line to find actual pictures of the larvae themselves. So I guess I have my solution, and one more piece of the puzzle that finally fits. And without that horsefly, I'd still never know it was right under my nose all this time. Amazing how little resemblance the "youth" have to their adult forms!!

Petco is notorious for selling bog plants as aquatic plants. I'll take a stab at id's: #1 pic looks like an anubias coffeefolia - aquatic #2 & 3 look like 'banana' plant - bog #4 at first I thought java fern, but the runners makes me think sagittaria - aquatic #5 ? another java fern, sagittaria or sword - if so aquatic #6 no idea but probably a bog plant

Flea beetle, I'd guess. You can look up ways to deal with them, but if you're trying to stay organic, there aren't that many options at this point. Releasing beneficial nematodes to destroy the larvae when they are in the soil is one, but there is timing involved, so do the research on that for your area. You often see dusting the plants with diatomaceous earth as an option. Diatomaceous earth doesn't differentiate between pests and beneficials, though, so if your strategy involves beneficials, that's something to think about. Trap crops are another option. I don't really get them on my tomatoes because they love eggplant much more. I've heard flea beetles like radishes and other brassicas even more, but that doesn't seem to be the case in my garden. They do some minor damage, but they seem to love the eggplants the best. This year, I interplanted flowering plants in my veggie garden that produce clusters of small, open flowers and let some of my herbs go to flower, as these types of flowers attract beneficial predators that parasitize the beetles. I've seen a surprisingly low level of flea beetle damage this year. Even my eggplants only have a few holes here and there from flea beetles, and whereas last year brushing the eggplants would produce a frenzy of hopping beetles, I only see the occasional flea beetle now. Unless infestation is severe enough to result in extensive damage to foliage, I generally look at the damage as cosmetic and just accept that it happens. Young plants are a different story, as they can be overwhelmed by a bad infestation, which is why I wait until eggplants are fairly large and robust before planting them out.