That may do the trick. While chickens can glean some nutrition from foraging, it is the rare forage that can supply the diverse nutrition chickens need to maintain production, body maintenance and disease resistance that a complete chicken feed can. These aren't your grandparent's chickens. Grass has almost no nutritional value to hens. The seed is ok for part of the nutrition but is very limited in essential amino acids. The bugs will supply some but the chickens will wipe them out in short order.
When did you start this experiment.
I once met a neighbor at the local feed store. He said he wanted to buy some of my birds because he said his hens were 'broken'. He said they quit laying eggs. I asked what he was feeding and he said, "scratch". I said, "what else". He said, "just scratch".
I said, "you're starving them". I told him to get a proper layer feed and lose the scratch. A month later they started laying again.