According to this: https://docs.google.com/spreadsheet/lv?key=0AgYOUdPlRXN-dEpUOUtKdDNqa29DN0cyam45Mlo5N3c&f=true&noheader=false&gid=3
It seems like Austere bees only produce powdery combs in a desert biome. You might want to look into Creepy bees instead, slower production of powdery combs...