I'm in Houston, TX. I placed the basil on the south side of the herb spiral, where it almost always gets sun. My insectary plants are on the north half, though to some degrees either east or west. So it's a possibility that the basil is too far away from the insectary plants. I'm quite certain it's leaf miners that are bothering my basil, I see a few leaves with the characteristic white lines that I pinch off. The damage is not too bad on my basil. But I have no idea what's eating my spinach, and I would say the damage for them IS extensive. This is despite the fact that the spinach IS next to a few of the insectary plants. I've never seen the culprit, but the young leaves barely have a chance to grow an inch out of the ground before they start getting eaten, and the holes in the larger leaves are very big. I'm not going to have any spinach to eat at this rate.
Thanks LW for the suggestions. I'm planning on adding a crescent hedge around my spiral and I'll add yarrow and lantana on my list of possible plants to include.