I agree with Lucy, that is either slug or snail damage. As far as treatment with Ferroxx goes, the warmer, the breezier, the more humid the climate, the more you have to use it.
It is probably not a grasshopper or locust. They are chewing insects often causing damage starting at the leave's edges, not in the middle.
Snails and slugs have 'rasp like jaws' scraping off tissue, layers at a time. You can clearly see that your husbands plant has damage in layers.
The best time to find them active is an hour after dark. By pointing a flash light at the ground near your plants, you should be able to find them out and about in the reflected beam of light.