How many mantises are in the egg case? Nick December 10, 2020 00:05 Updated About 75 to 200 tiny mantises will hatch from the egg case. Related articles Why should I release my young mantises soon after they hatch? What should I do when the egg case hatches? How long will it take for my praying mantises to hatch? Can my mantises escape their mesh habitat? Can I raise butterflies and praying mantises in the same habitat? Comments 0 comments Please sign in to leave a comment.