Those look like maggots, not chicken worms. Everything looks really wet, which is probably contributing. Maggots are larvae from flying insects that lay their eggs in the droppings after they are deposited, they hatch and you have maggots. So you may need to do something to get your moisture level down, and depending on your space and number of birds, you may need to clean up droppings more often, or you may need to give them a bigger area, to keep droppings from building up. The drier it is the better, droppings will dry out faster and less likely to have an issue. Inside my coop I have poop boards under the roosts that I scrape daily and my covered run has a very deep layer of shavings (deep litter method-it only works if it stays pretty dry). Wet conditions and droppings build up can also mean increased ammonia fumes, which can be bad for your birds respiratory systems. If you have a lot of flies being attracted to droppings build up, you also increase the risk that a bird with a wound or droppings stuck around the vent will be affected by flystrike, so good to keep the population of those down as much as you can.