The greater wax moth, Galleria mellonella, is an insect known for its relationship with honey bees. In its larval stage, it is a significant pest for beekeepers by infesting hives. However, these caterpillars are also a subject of scientific inquiry due to their unique biological traits, giving them a complex role in both ecological and scientific contexts.
Identifying Greater Wax Moth Larvae
The greater wax moth undergoes a complete metamorphosis through egg, larva, pupa, and adult stages. Adult female moths lay clusters of creamy-white eggs in the cracks of a beehive or on stored combs, which hatch in three to five days. The larval period can last from one to six months as the caterpillar molts and grows.
Upon hatching, the larvae are small and whitish but grow to over an inch, becoming grayish with a dark brown head. Their habitat is almost exclusively within honey bee colonies or stored beeswax combs. To enter the pupal stage, they spin tough, silken cocoons.
Damage Caused to Bee Colonies
Greater wax moth larvae can be destructive to honey bee colonies, especially weak or stressed ones. The larvae tunnel through beeswax combs, consuming wax, stored pollen, honey, and even honey bee pupa cocoons. This activity damages the comb’s structure and depletes the colony’s food reserves.
As they move, the larvae spin extensive silken webs that create a network of tunnels. This webbing can cover frames and entangle adult bees. A severe infestation is characterized by disintegrated combs filled with silk and larval feces, known as frass.
In a condition called bald brood, bees uncap cells containing pupae killed by the larvae. A heavy infestation can cause the bee colony to abscond or lead to its complete collapse.
Managing Greater Wax Moth Larvae in Apiaries
Managing wax moths starts with prevention and maintaining strong bee colonies. Populous hives can better police their space and prevent moths from laying eggs. Good ventilation, avoiding empty hive space, and storing unused combs in well-lit, airy locations can also deter moths, as the larvae prefer dark environments.
If an infestation occurs in stored equipment, several control methods exist. Freezing combs for 48 to 72 hours kills all life stages of the moth. For severe cases, destroying the affected frames may be necessary to prevent spread. Some beekeepers use fumigants, which require careful handling and are only for use on stored combs, never in active hives with bees.
A biological control agent, Bacillus thuringiensis (Bt), is a bacterium toxic to wax moth larvae but harmless to bees and humans. Products with specific Bt strains can be applied to combs before storage. This is part of an Integrated Pest Management (IPM) strategy that combines tactics for sustainable pest control.
Scientific and Commercial Uses
Greater wax moth larvae are commercially valuable. They are bred and sold as high-fat live food for captive animals like reptiles, amphibians, and birds. Anglers also use the larvae as bait for fishing.
In scientific research, the larvae serve as model organisms. Their immune systems have similarities to mammals, making them useful for studying host-pathogen interactions and new antimicrobial drugs. Their low cost and rapid life cycle allow for large-scale preliminary screening of compounds.
A significant application is in bioremediation. Researchers discovered that Galleria mellonella larvae can consume and biodegrade polyethylene plastic, a persistent pollutant. The caterpillars break down the plastic’s polymer chains, a process that normally takes centuries.
This discovery has spurred research to identify the specific enzymes in their saliva and gut responsible for this ability. The long-term goal is to develop enzymatic solutions for plastic waste.