Row covers prevent moths from laying eggs, but they also prevent insect pollination. Not all garden plants require insect pollination though.

I have found row covers to be quite the pain to use. Easily torn up by winds and they have to be constantly moved and adjusted when trying to access the plants. Pretty much impractical for trellised plants too.

BT isn't at all harmful to people or pets or bugs in general. The strain you would use for caterpillars is harmless to almost everything else. It is just a naturally occurring bacteria. It's use simply increases the number of these bacteria on plants it is applied to. There is no risk of developing a bacterial infection from these.

While it is generally regarded as effective, a heavy presence of the pest may not be fully controlled by it.

Traps can be used for some moths, but they usually work by using an attractant. The potential problem with all traps is that while they will kill some, they may attract more than they kill resulting in a greater problem than you would have had otherwise. This is one of those things some gardeners end up swearing by them and others swear at them.

thanks for your help, I really appreciate it. I was thinking of row covers, but for some reason I had it in my head that they were for extending the growing season and I don't need that in my long long summer. :o) Winds are a problem here, but not generally in the summer, just spring and fall, and I am assuming (??) that moths lay their eggs in the summer? Maybe not, not the tomato horned worm eggs, I just say this because it would be nice not to always have to remove the covers to say pick tomatoes.
I had googled a little bit about BTI, which said it caused problems in rats, not that I am worried about them, but as I find horned worms in our pool, I know the birds eat them and I didn't want to hurt them, and since they do so many studies for humans on rats, I just had a niggling doubt about intestinal problems that BTI MIGHT give humans. So, if there's a BTI just for caterpillars, that might alleviate my concerns.

You might find this article from Ohio State University helpful in assessing whether you are comfortable with the use of BT or not.

I was thinking about your predicament with caterpillars and thought to tell you of an experience I had this year. I really do not have much of a caterpillar problem other than cabbage moth larvae on various greens, but I no longer do anything to control them as they don't seem to last long enough to do much damage.

My means of keeping the caterpillars in check was done quite accidentally. For years I had a bird feeder which primarily attracted finches and doves. This year I added a couple more feeders as well as a bird bath. The number of birds in my yard at any given time increased dramatically. I also have an open air compost pile that sees kitchen scraps dumped on top rather than mixed in and the birds seem to love pick at the new additions.

It isn't uncommon for me to head out to the garden area and see dozens of finches take off together. What are those finches doing in the garden? Well, they aren't bothering the plants so I have to assume they are eating insects and possibly some weed seeds.

The bird control of caterpillars has been so successful that it has had it's drawbacks. I had several Swallow tail moth caterpillars on some dill and fennel that I was really pleased to see. I took my kids out to show them and then we had fun on the internet reading about them and the beautiful butterfly they turned into. Unfortunately they didn't last more than a few days. I suspect the birds ate them! ;-(

Still, this one drawback aside I think you would benefit by taking reasonable measures to attract bug eating birds to your garden. It is usually as easy as providing a source of food and a source of water. You can also attract the birds right to the plants you need to most protect by putting a shallow dish with an inch or less of water right next to those plants or install a bird feeder right next to them. the only caveat is birds are messy eaters and will scatter the seed around and it can become a weed in no time. As such you might consider the suet feeders or bird seed 'cakes' instead of loose seed when feeding in the garden area.

The shallow dish of water also often attracts pollinating bees.

yeah... I have finches like crazy (I do feed them, even growing millet)... and I know you are right... and I think even ravens feed in my garden, because it has to be some big bird, maybe pigeons? I saw a pigeon the other day, that is accidentally dropping very large (how did I miss this? I looked the other day) tomato horned worms into the pool. But apparently it's not enough. I didn't realize how effective my daily picking and throwing was before... it always seemed a never ending CHORE, but this year I got a good idea, seeing the decimation. :D It's the little green ones that I miss... usually the larger THW's are pretty easy.USUALLY.
When I moved here I stopped trying to plant butterfly attracting plants, but some, I can't help it, I love them, like lavender.
Okay... I will try BTI... *sigh* thank you!

You wrote: "Okay... I will try BTI"

Don't bother, because it won't work. Bti is Bacillus thuringiensis israelensis. It's used against mosquito larvae.

The form of Bt to use against caterpillars is Btk -- Bacillus thuringiensis kurstaki. And then, only before they are half-grown. Older cats easily "escape" the adverse effects of Btk.

okay good... I was wondering how to tell the regular Bacillus from the one which attacks caterpillars. Thanks! :o)yeah... well, I can get the tomato horned worms, they are so easy to tell when they are young or old. The small green ones, I will try the row covers and dust... I am so programmed to be afraid of 'pesticides' it's giving me the heebie jeebies, but I know it's safe, I believe people on this forum. :o) or should I? :D
I may have more time next year for 'picking and throwing' so that will help too. Or maybe whatever that made them so prevalent this year will be different next *hope* *hope*

I've been using BT against the caterpillars my garden is covered with. Read the label to know what the type of BT is intended against.
There is a BT specifically for stuff like mosquitos and other aquatic larva.
There is a BT that works against certain soil dwelling larva.
Finally BT that makes caterpillars sick (note that they must eat it to be effective.)

I have had such a heavy infestation of several types of caterpillars that I can really tell a difference when I've been spraying regularly (I have not been able to find the dust version locally yet.) However rain has washed away much of my efforts.

I have been trying to encourage birds but so far they have mainly been after the seeds this season and ignoring the worms.

Last spring I got to watch a cardinal attack a huge horn worm on a tomato plant, it was interesting to catch myself cheering for the bird through the window. I think plenty of perches around the plant for the birds to land on while trying to pull the caterpillars from the plants must be necessary for this to work.

There are some 35 different Bacillus thuringiensis bacteriums identified today and each has uses for some insect pests. You most likely have these bacteriums around you already, just not in quantities necessary for control of the pests. BTK, Bacillus thuringiensis - Kurstaki is the primary mixture used to control leaf eating larva of many insect species and is sold as Dipel, Thuricide, and a number of other names.
BTI, Bacillus thurigiensis - isrealensis, is for the control of the larva of Blackfly, Fungus Gnats, and mosquitoes.
BTSD, Bacillus thuringiensis - San diego, can be used to control Colorado Potato Beetles, some Black Vine Beetles, Boll Weevils, and Elm Leaf Beetles.
There are a number of others with more limited use. A major part of organic insect control is properly identifying the pest you have and starting with the least toxic means of control find what works, but use the apporpriate means of control.

I agree, which is one reason I wasn't really considering traps. Once a few years back, I think I had the smallish green caterpillar identified, but I can't remember what I thought it was. There's articles online about a recent Australian moth infestation of California, but I don't think that's my problem, these've been around for the time I've been gardening here in Sacramento.
It looks like a soybean looper in it's light phase, but it never has a dark phase. I am extremely familiar with it, as I have picked them for years. :D *sigh* I guess next year, if I have a chance I will pick one and take it to my local extension.

I got together with a Master Gardener and other serious gardeners in my area, found that those little green caterpillars were extremely common this year... not just to me. Also, when I mentioned BT, was told that people found that the darned worms got immune to it! *sigh*