The wax moth is a significant pest known for its destructive impact on honey bee colonies and beekeeping operations globally. While the adult moths are harmless, the larval stage causes substantial damage by feeding on beeswax and other hive materials. This insect is a major threat to apiculture because its presence quickly compromises the integrity of the hive structure and leads to the loss of valuable resources. The wax moth is a scavenger that thrives in the honey bee nest, especially when the colony is weakened or the comb is left unattended.
Identifying the Two Major Species
Beekeepers are primarily concerned with two species: the Greater Wax Moth (Galleria mellonella) and the Lesser Wax Moth (Achroia grisella). The Greater Wax Moth is the more destructive and common of the two pests. Adult Greater Wax Moths are typically pale brown to gray, reaching 15 to 20 millimeters long, with their wings held in a distinct roof-like shape.
The Lesser Wax Moth is noticeably smaller, measuring 10 to 13 millimeters, and has a slender, silver-gray to dull-yellow body. Unlike the Greater Wax Moth, its wings lack the distinct roof-like fold, and its larvae are often more solitary in their tunneling. Both species are attracted to the complex blend of wax, pollen, and larval debris found within honey bee comb.
Understanding the Destructive Life Cycle
The wax moth undergoes complete metamorphosis, passing through four stages: egg, larva, pupa, and adult. A female typically lays 300 to 600 eggs in clusters, depositing them into cracks and crevices within the hive or on stored comb, safely out of reach of the bees. Under optimal warm conditions, the eggs can hatch within three to five days.
The larval stage is the most destructive phase, as the newly hatched larvae immediately tunnel into the beeswax comb. While the larva can digest beeswax, it relies on impurities like stored pollen, bee cocoons, and larval cast skins for necessary protein. As they tunnel, the larvae leave behind silken webbing and granular fecal matter known as frass, which contaminates the comb. Larvae are active in warm temperatures, reaching up to 28 millimeters, with the larval period lasting from 19 days up to five months depending on temperature and food availability.
The mature larva seeks a sheltered location to pupate, often chewing a boat-shaped cavity into the wooden frames or hive body to secure its cocoon. Inside this tough, white silk cocoon, the larva transforms into the pupa, a stage that can last from a few days to two months. The adult moth then emerges; it possesses reduced mouthparts and does not feed, focusing solely on reproduction.
Impact on Bee Colonies and Stored Comb
The destructive tunneling of wax moth larvae damages the structural integrity of comb in both active colonies and stored equipment. Larvae readily consume brood comb because it contains protein-rich remnants of previous bee generations. In active hives, silken tunnels often run just beneath the cell cappings of developing brood.
This tunneling can cause “bald brood,” where bees remove cappings to clean the area, or the more serious “galleriasis.” Galleriasis occurs when emerging young bees become entangled in the dense, sticky silk webbing, preventing them from escaping their cells and causing starvation. The resulting comb destruction, frass contamination, and inability of new bees to emerge place immense stress on the colony.
The impact extends beyond the living colony, as the pests ruin stored comb, a valuable asset requiring significant bee energy to produce. Infestations are often secondary problems, taking advantage of colonies that are weak, stressed, or queenless, quickly overwhelming them and causing them to abandon the hive or die. Larvae also damage wooden beekeeping equipment by chewing components to create pupation sites, necessitating costly repairs or replacement.