The famous temple is dedicated to Lord Karna (of Mahabharath)- a rare thing by itself !!
Belief is that when devotees ask for help Lord rush to him in the form of Mahu (bee) and help them to solve it. Thus the Lord became Mahunag.
Generally, devotees pray to this God for solving their Legal and family matters. There will be a rush of devotees on Sundays which is auspicious.
Temple is 25 kilometers from Karsog, which is about 100 kilometers from Shimla.