I live in AZ, and have just started gardening. I have a raised bed garden in which i have two troubled bell pepper plants. whatever is eating them started on the outside of the leaves, and now there are holes in nearly all of the leaves. the stem(if that's what you call it) of the plant is also being eaten; it's crusty and white. I've been looking everyday for the past couple weeks and i've been treating the plants with insecticidal spray. i've seen no noticeable groups of bugs or large bugs, except for these small, transparent looking bugs that sit on the underside of the leaves. i've checked during the night, but these bugs are the only ones i've seen. there's not even that many of them, and they are typically on new growth. please help, i've done so much research and haven't determined the culprit yet.

here's my pictures of the damage/the