Troubleshooting plants: Leaves drying up and falling off, others have holes

Hello all,
 
I am growing peppers for the first time this year and I am finding my plants are not fairing as well as some of the beautiful ones posted here. I am not sure what I am doing wrong, but I've got a lot of plants that have leaves drying up and falling off near the bottom of the plant. I am also experiencing holes in the leaves, where it looks like something took a bite out of it, but the cuts seem to be too clean to be an animal. Can anyone help in what I could do to prevent this or if I am doing something wrong? I am in the Sacramento area, so we routinely get dry heat in the 100Fs. I have all of my plants in grow bags under a shadecloth and I water about every other day, sometimes skipping an extra day of watering if they seem well. I do not notice any bugs on them except for some spiders that are making webs around the rims of the bags, although I could certainly be missing something I do not know I should look for.
 
Here are some photos of what I am looking at:

Wow you definitely have something chewing on those plants. Probably a caterpillar or slug or something. As far as the webs you're seeing, make sure they're not spider mites. They are very very very small and hard to see. You mights need a magnifying lense or something to see them.

The semicircles cut out from your leaves looks like the damage from leafcutting bees. I have them here too. They can make the plants look ugly, but I've never had them actually kill a plant, nor do they interfere with flowering and fruiting. In fact, they are pollinators just like honeybees. You can protect your plants from further damage by covering them with mosquito netting or the like.

You have to keep checking at first light and after sundown. I get big grasshoppers every now and then that do that kind of damage. Whatever it is is most likely hiding from the heat during the day and feasting on the only greenery around at night.

Thanks guys, I will keep an eye out tonight and in the morning. Looks like I might be investing in some mosquito netting.
 
Any idea on the leaves drying up and falling off? I am wondering if I am over or under watering as I am not seeing a lot of flowering yet either.