After the death of Eric O'Grady, the third Ant-Man, against the Descendants, the latter choose to take advantage and made a Life-Model Decoy of him to act as a double agent in the Secret Avengers. He later turned his Avengers teammates and became Black Ant.
Notes:
First appearance in Secret Avengers (Marvel, 2010 series) #24 by Rick Remender and Gabriel Hardman.