How do you kill screaming mantis on mgs4

inject youself with the needle to get rid of those annoying webs then shoot her dolls(sorrow and mantis). after wailing on the dolls for a while theyll fall off and you can grab them, once you have both of them you can use them against her. also when meryl tries t kill you knock her out then when she wakes up grab her and inject the needle into her so her webs go away.