Ivermectin is effective against a large variety of worms and works also against mites . Some people use it for chickens. It is expensive. Crush 2 tablets and soak in some water overnight, then make 1 gallon of water and provide as the sole source of water for 2 days. If this is the first time you are worming the flock, repeat in 12 days.
Some people worm once a month.
Some people use garlic and believe it's a wormer - apparently garlic is a mild form of natural antibiotic and acts to a small degree in limiting the growth of nutrient robbing bacteria from the gastrointestinal tract. There is no effect against internal parasites such as worms.