2.2. Wax moth larvae
Upon hatching, the greater wax moth larva is an off-white colour and 1-3 mm in length (Table 1; Fig. 2). The newly hatched larva immediately begins to eat and spin webbing (Fig. 3). The head capsule is yellowish and smaller than the more pronounced prothoracic segment (Paddock, 1918). The presence of stemmata on the head can be used to differentiate between greater and lesser wax moth larvae (Ferguson, 1987; Fig. 4). The thoracic legs are well developed when the larva first emerges but the abdominal legs are not visible until the larva is about 3 days old. A greater wax moth larva moults 7 times throughout its development. Most of the growth and size increase happens during the final 2 instars (Fig. 5). Larval development lasts 6-7 weeks at 29° - 32° C and high humidity. A mature greater wax moth larva (Fig. 6) is approximately 20 mm in length (Paddock, 1918). Its body is grey in colour with a brown prothoracic shield having a broad band across it. The head is slightly pointed, small, and reddish with a v-shaped line opening towards the front of the head (Paddock, 1918). A greater wax moth larva goes through 8-9 stages (moults) over the course of its development at 33.8° C (Chase, 1921; Charriere and Imdorf, 1999).
Mature greater wax
moth larvae are capable of boring into wood and often make boat-shaped
indentations in the woodenware of the hive body or frames (Fig. 7). After
finding a place in the hive to pupate, the larva begins spinning silk threads that
will become the cocoon (Fig. 8), which they attach to the excavated
indentations (Paddock, 1918). One often finds many of the cocoons congregated
in areas around the perimeter of the bee nest in high infestations (Fig. 9). After
hardening, the outer layer of the cocoon is somewhat tough while the inside
remains soft and padded. Cocoon construction times can be variable due to
temperature and humidity though the average cocoon construction takes 2.25 days
to complete (Paddock, 1918). The larva
becomes less active as the cocoon is constructed. The larva creates an incision
point in the cocoon near the head through which to escape as a fully formed
adult (Paddock, 1918). Greater wax moth larvae tend to congregate in the hive
whereas the lesser wax moth larvae are more likely to be found individually in
tunnels within the comb (Williams, 1997).
Fig. 4. Diagnostic characteristics on the head of greater and lesser wax moth larvae. The greater wax moth larvae head (A) has four stemmata on both sides (small, pale ovals are arrowed). Image B is redrawn from Ferguson 1987 and shows the location of the four stemmata. The lesser wax moth head (C) does not have the four stemmata (also shown in D, redrawn from Ferguson 1987). Photographs (A and C): Lyle Buss, University of Florida.
Fig. 5. Diagnostic characteristics on the spiracle of greater and lesser wax moth larvae. The greater wax moth larvae spiracle (A) has a yellowish peritreme (arrowed, pale) of uniform thickness (also shown in the inset image redrawn from Ferguson 1987). The lesser wax moth spiracle (B) has a black peritreme that is thicker on the caudal margin (arrowed, also shown in the inset image redrawn from Ferguson 1987). Photographs: Lyle Buss, University of Florida.
Fig. 6. Greater wax moth larva in a wax cell from the brood nest. Photograph: Lyle Buss, University of Florida.
Fig. 7. Greater wax moth larvae eating wax comb down to the plastic foundation. Notice the characteristic webbing and frass associated with the feeding behavior. Photograph: Lyle Buss, University of Florida.
Fig. 8. Wax moth damage to woodenware. The larvae excavate furrows in the wood and they attach their cocoons to these furrows. Notice the boat-shaped indentations in the wall of the hive. Photograph: Ashley Mortensen, University of Florida.
Fig. 9. Greater wax moth larvae (top), pupa (middle), and cocoon (bottom). Photograph: Lyle Buss, University of Florida.