They all love them, but i heard on the radio about lungworm in dogs, and to be honest it never occured to me about the hens getting it. These two are mad over it, Harrier on the left will only eat slugs and Mandi on the right will only eat woodlice, a devastating pair Thanks
Yes, earthworms in particular can harbor roundworms and other chicken parasites. However, as long as you watch out for any signs of internal parasite infestations (worms in the droppings, lethargy, emaciation, etc.), and de-worm if necessary, it is fine to let your hens eat whatever insects they want. I let mine eat plenty of earthworms, and have never had a problem. Besides, they love it!
Woodlice, worms, and slugs are usually fine for chickens to eat. In the wild, chickens would eat all of these things. They can harbor parasites like tapeworms that require an intermediate host, however. Just keep an eye out for any signs of your chickens having worms (lethargy, weight loss, etc), and worm if necessary. Hope this helps!