New Khush Captcha For Buddy Press simply adds a new form of captcha to your Buddy Press registration and comment forms. With this new plugin you can easily solve the problem of spam bots registration and and prevent bots from spamming your website. The plugin also works for BuddyPress comment forms.
But you cannot use this plugin for WordPress comment forms. So if you have BuddyPress activated on your WordPress installation the install and activate Khush Captcha For Buddy Press plugin.
After activation visit its options page from WordPress admin settings menu and set custom Khush Captcha Blank Text Message and Khush Captcha Error Text Message.