I think hmwalatka whole intent is very different from most of us. Chickens will be valued as a tool more than as a product. Duration has potential for being very short-term with birds going out about time cicada emergence starts and then put back into a more conservative mode once cicada emergence stops. This means more birds will also be needed, at least relative to what I run. I can easily get suppression of grasshoppers and the like with about 20 birds per acre, and fewer birds are required if I hold back a little on feed but care must be taken to keep birds from expanding range to compensate. Expanding range will get them away from blueberry plants to be protected and beyond your area where you plan on protecting them from predators. A problem I see with this application is the birds will first have to suppress the regular insect biomass before taking on a potentially much larger amount coming in as extremely mobile cicadas. If the hatch is heavy like we experienced a couple years ago, the chickens will have a hard time even putting a dent in them since they will be replaced as quickly as consumed by insects coming in from areas outside. I call the insects coming in from the outside drift. One of my free-range flocks that is fed very little goes to considerable lengths to capitalize on the drift but they will only consume so much before targeting green plant materials and seeds. They seem to like a balanced diet. Also, some birds seem more than content doing most if not all their feeding from feeder which not benefit the cicada control efforts. Also think about life-stage of the chickens. For me, juveniles and chicks are much more interested in animals as eats but larger juveniles at least will be required to tackle such large game. I recommend not using Cornish cross or bantams for this.
Hopefully there are some large trees nearby that will take the brunt of the egg-deposition coming from the female cicadas / locust.