Increase of Spam Bots at This Site?

[PrimalxConvoy]

I've noticed that, in the past few days, several spambots have infiltrated this site and have posted multiple spam threads in most of the sub-forums here.

Also, even if I block them (which I have), their posts show under the "latest post" description under each sub-forum.

Please could this be fixed?

 

[CoffeeHorse]

I can do that maybe once a week, but no more.