Forum:Bot-created gibberish pages, Captcha solution?

For a couple months now, there have been some gibberish pages created by anonymous users at the Virus wiki. So far, no legitimate pages have been vandalised. Typical pages have looked something like this:

Title: Bekomin Content: So nice to hear. Auth[e]r is the best. Thx u a lot. Hope to hear some more information So  nice to hear. Auth[e]r is the best. Thx u a lot. Hope to hear some more information

Another example:

Title: Battlecores I wanna to decide some of questions in this area. Could u help me to do it? I wanna to decide some of questions in this area. Could u help me to do it?

Note: Brackets placed on "Auther" because this word (now) triggers the spam filter when next to "is the best".

I have done searches on some of these text strings (try googling "Auth[e]r is the best" with the quotes and no brackets around letter "e") and found that thousands of forums, guestbooks and other open areas of the Internet are having problems with this rubbish. I am certain that something automated is doing this.

I was thinking that a captcha would be the perfect solution to this problem. According to the Wikia Help page on captchas, these are only used when an anonymous user tries to insert a link or blank a page. Would it be possible to make a captcha required for the creation of a new page by an anonymous IP?

Many thanks to Uberfuzzy, who has deleted a number of these pages when I have been away.