There are 2 bees one is Blue bee which produces the Gendustry blue dye that doesn't work. The Prussian bee does produce vanilla blue dye. It requires a water bee which I haven't been able to find yet. Water bee would also be useful in making the Lapis bee as well. I ended up just doing the wool + lapis route. Just asked because the only way to produce any meaningful blue dye is to have mass amounts of sheep. I guess you could have a massive hemp farm as well for the string. Just looking for a more efficient way than 1 dye per stack of blue wool.