I would imagine if a chicken actually ate it, she would die. And note to self if a black widow bites you, you will not feel the bite. Then you will get symptoms of muscle cramps, nausea, and head ache approximately 30 mins later then a coma. And within much time after that if you don't get a black widow anti venom shot you could pass away. I would take black widow problems seriously. My aunt got bit when she was a child and it almost killed her. Seven spray may work. And spray it around water hydrants and the sides of buildings. Also this winter when the spiders are dormant remove any old wood piles and garbage from your property. As well in the coop permethrin mite spray is safe for chickens and it will kill spiders. Just don't let the permethrin get into water systems, it can harm fish.