miguelpinheiro on "[Plugin: Wordfence Security] Live traffic is using https"

Mark,

A public visitor can access the/wp-admin/admin-ajax.php with the right url for http.

Because your question, I looked at admin_url() reference -
http://codex.wordpress.org/Function_Reference/admin_url and now I have a suggestion to you:

public static function wp_head(){
                $URL      = admin_url('admin-ajax.php?action=wordfence_logHuman&hid=' . wfUtils::encrypt(self::$hitID));
                $URL_HTTP = admin_url('admin-ajax.php?action=wordfence_logHuman&hid=' . wfUtils::encrypt(self::$hitID),'http');
                echo '<script type="text/javascript">var src="' . $URL . '"; if(window.location.protocol == "http:"){ src="' . $URL_HTTP . '"; } if(window.location.protocol == "https:"){ src = src.replace("http:", "https:"); } var wfHTImg = new Image();  wfHTImg.src=src;</script>';
        }

This code preserves the old behavior, but changes the resulting URL when the protocol is http.

Hope this helps. Let me know.

Miguel