In the 19th century, chickens were kept in small flocks on diversified farms and were almost self-sufficient, mostly feeding themselves on insects, grain spilled by cattle and horses, and plants around the farm. Poultry generally had free rein of the barnyard and this laissez-faire method of chicken-keeping worked well, but laying hens also required calcium to strengthen the egg shells and supplements were provided. Where available, oyster shells were an excellent source of dietary calcium. Where not, flaked, green bone was used. It was also not uncommon for farmers to let the hens into the garden for an hour or so for supervised bug control.