When to Ask for A Raise

As you all know, I have been blogging for a couple of music blogs for several months already. If I am not mistaken, I have been blogging for this guy for around 8-9 months already. Recently, the owner of the blogs I blog for added several more sites for me to work on. Although I see the new work as a new source of income (which it is), I feel that with the quantity of work that I produce in a week, I feel that the compensation I receive is insufficient.

My dilemma is whether I should ask for a raise or not. But I am afraid that if I do ask for a raise, he might just drop me and hire someone else. I love the job I have since it lets me listen to a wide range of music, including some past favorites that I haven't listened to in a while. Not to mention the fact that the guy pays me on time, every time. But what do I do???