what are black worms in mixture of cow dung and soil
I tried to make organic manure at home by composting cow dung. Now there are black worm like creatures running in the compost.
I believe you need to reevaluate your composting method, because properly composted manure is going to produce a lot of heat that will prevent bugs from getting into it. This article has some basics of composting manure: https://www.gardeningknowhow.com/composting/manures/cow-manure-compost.htm