Normal brood development

Making the comparison

In order to diagnose AFB, it is important to understand the process of normal worker bee development. Identifying brood symptoms involves comparing the appearance of brood that looks abnormal with the appearance of healthy brood.

Healthy development of bees

The developmental stages of healthy worker brood are outlined in Fig. 6. Three days after the queen lays an egg it hatches into a pearly white larva. At this stage, the larva appears as a small c-shape in the bottom of the cell.


 Figure 6: The developmental stages of healthy worker brood

Figure 6: The developmental stages of healthy worker brood

Compare picture (above) to abnormal development

Over a four-day period, the larva remains in this c-shape, greatly increasing in size until it appears to completely fill up the cell. On the eighth day (after the egg was laid), the larva stretches out along the lower wall of the cell in preparation for changing into the adult form (called the “prepupal stage”). On the ninth day, the cell is capped over with wax by house bees.

On the 12th day, the larva pupates and the form of the adult bee takes shape. The pupa is initially white in appearance, but gradually changes into its adult colouration. On the 21st day, the new adult worker bee chews a hole in the capping and emerges.

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