On Moon Guard, blue seems to be one of the more scarce colors, with red a close second. Green, at least for Ala, seems to be as common as the brown.

In total, I think she spent two fairly steady weeks out in Uldum before her blue finally came to say hi. When I started there was a fairly clockwork eight-hour spawn timer he favored, but the last week he was leaning more to the fifteen-hour mark.
I caught a total of four farmbots while camping. Curiously, I witnessed an air-walker the night before blue popped, and I ended my report to Blizz with:
"You see the darndest things sitting out in Uldum while camping a tame for a Blue Madexx".

Hmm....
My arting buddy Peachie made me name it after
her mascot. I couldn't say no. xD
Thanks, Novi!

Huge grats on your 'nanapider too!