Differential expression of miRNAs at four metamorphic stages (CK, 4 h, 12 h, and 24 h) by hierarchical clustering in `Baiye 1’. Red indicates that a gene is highly expressed at that stage, whereas green indicates the opposite. The absolute signal intensity ranges from −2.5 to +2.5, with corresponding color changes from blue to green, yellow and red. The signal of expression was detected by microarray with four probe repeats. BY-CK: control; BY-4: 4°C for 4 h; BY-12: 4°C for 12 h; BY-24: 4°C for 24 h.