If you have ever opened a hive or a box of stored frames and found a mess of silk webbing, dark tunnels, and crumbling comb, you have met the wax moth. It is one of the most common beekeeping pests in the world, and it is also one of the most misunderstood. Wax moths do not attack strong colonies. They are scavengers, not predators. They move in when a colony is too weak to patrol its own comb, or when frames sit in storage unprotected. Understanding that distinction changes your entire approach: the best defense against wax moths in a living hive is colony strength, and the best defense in stored equipment is proper handling. This guide covers both.
What are wax moths and what do they look like?
Two species cause problems for beekeepers worldwide. The greater wax moth (Galleria mellonella) is the more common and more destructive of the two. Adults are grey-brown, slender moths about 12 to 20 mm long with a total wingspan of up to 40 mm. Females are larger and darker than males. The lesser wax moth (Achroia grisella) is smaller (about 10 to 13 mm), silvery-grey, and causes less damage but still infests stored comb. Both species are attracted to beehives by the scent of beeswax and old brood comb. Female moths enter hives at night, when guard bees are less active, and lay eggs in cracks, crevices, and the gaps between frames. A single female can lay several hundred eggs in her lifetime.
The adults do no direct damage. They do not eat, since their mouthparts are reduced. The destruction comes entirely from the larvae. Greater wax moth larvae are thick, greyish-white caterpillars that grow up to 28 mm long. They tunnel through comb, eating beeswax, pollen, cocoon silk left by bee pupae, and other hive debris. As they tunnel, they leave behind silk webbing and dark cylindrical frass (excrement) that is the most recognizable sign of infestation. When ready to pupate, the larvae chew shallow pits into the wooden surfaces of frames and boxes to anchor their cocoons, leaving permanent scarring that weakens the equipment.
The entire lifecycle, from egg to adult, takes roughly 6 to 7 weeks at summer temperatures (around 30°C / 86°F). In cooler conditions the cycle slows considerably, and below about minus 7°C (19°F) wax moths cannot survive at any stage.
Why do wax moths infest some hives and not others?
Because strong colonies kill them. A healthy colony with a good population of workers patrols every surface of the comb. Guard bees detect and remove moth eggs and small larvae before they can establish. In a strong hive, wax moths are a nuisance that never gains a foothold.
The problem starts when the colony weakens. Queenlessness, heavy Varroa loads, disease, starvation, or dwindling from pesticide exposure all reduce the population to the point where bees can no longer patrol the entire comb surface. Wax moth larvae exploit the unguarded zones, and once a tunnel network of webbing is established, the bees often give up and abandon those frames entirely. Monitoring and treating Varroa before infestations weaken the colony removes one of the leading causes of the weakness that lets moths in.
Dead colonies (deadouts) and stored equipment are the most vulnerable targets. A box of drawn comb sitting in a warm shed with no bees to defend it is a wax moth buffet. Old brood comb, which contains pollen residues and pupal cocoon silk, is far more attractive to moths than clean honey comb or undrawn foundation. This is why stored supers after the honey harvest are the number one place wax moths do damage.
How do you identify a wax moth infestation?
The signs are distinctive once you know what to look for.
Silk webbing. White or greyish silk threads stretching across the comb surface and between frames. This is the most reliable early indicator. It looks like spider web but is more matted and contains bits of wax debris and frass embedded in it.
Tunnels. Larvae bore through the midrib of the comb, leaving visible channels that collapse the cells on both sides. Heavily infested frames look like they have been chewed from the inside out, with entire sections of comb reduced to a web-covered mass.
Frass. Small, dark, cylindrical pellets on the bottom board or between frames. This is larval excrement, and finding it during an inspection means larvae are actively feeding somewhere above.
Cocoon pits. Oval depressions chewed into the wooden surfaces of frames, boxes, and even plastic foundation. These are where mature larvae attached their cocoons for pupation. The pits weaken the wood and make equipment harder to clean and reuse.
Odor. Heavily infested comb produces a foul, musty smell that is unmistakable once you have encountered it.
Catching infestations early matters. A small patch of webbing on one frame is easy to deal with. A fully infested box with collapsed comb and hundreds of larvae is a write-off. Regular inspections using smart hive-monitoring tools help you catch population declines before moths exploit the gap.
How do you prevent wax moths in living colonies?
Prevention in an active hive is about colony management, not chemicals.
Keep colonies strong. A populous colony with a laying queen and adequate stores is its own wax moth defense. Requeen colonies with failing queens promptly. Understanding the queen's role in colony health reinforces why queen status is the first thing to check when a hive weakens.
Right-size the hive. Do not give a colony more space than it can patrol. A small colony in a double-deep hive cannot defend all that comb. Remove empty supers and reduce to the number of boxes the bees actually occupy. This is especially important in autumn when the population is declining.
Combine weak colonies. A colony covering fewer than 5 frames going into autumn is better combined with a stronger colony using the newspaper method. Splitting and combining colonies strategically is a year-round skill that also prevents moth problems.
Rotate old comb. Dark brood comb that has been through many brood cycles is the most attractive to wax moths. Replace the oldest three to four frames in each brood box every two to three years. Fresh comb is less appealing and also reduces the accumulation of pesticide residues and disease spores.
How do you protect stored comb and equipment?
This is where most wax moth damage actually happens: not in live hives, but in the shed, garage, or honey house where supers sit after the harvest.
Freeze first. Before storing any frames of drawn comb, freeze them for at least 48 hours at minus 15°C (5°F) or below. This kills wax moth eggs, larvae, and pupae at all stages. A standard chest freezer handles a few supers at a time. After freezing, wrap or seal the frames immediately to prevent re-infestation.
Store with light and airflow. Wax moth females avoid light and still air. Stacking supers in a well-lit, ventilated area (not a dark, warm shed) significantly reduces infestation. The traditional method is stacking supers in a tower with spacers or crossed sticks between each box so air circulates and light penetrates. Outdoors under a roofed shelter, open to breeze on the sides, is one of the best low-cost storage setups.
Bacillus thuringiensis (Bt). A biological control agent (sold as Certan or B401) that specifically targets wax moth larvae. You dilute it in water and spray it onto stored comb before stacking. When moth larvae hatch and begin feeding on the treated comb, the Bt toxin kills them. It is safe for bees and does not leave harmful residues. Bt is the best option for beekeepers who want effective moth control without chemicals.
Paradichlorobenzene (PDB / Para-Moth). A chemical fumigant sold as crystals that you place on a paper plate on top of the uppermost super in a sealed stack. The vapors kill moth larvae and eggs over several days. PDB is effective but must be used with caution: air out treated supers for at least 48 hours before returning them to bees, since the fumes are toxic to bees and unpleasant to humans. Do not use naphthalene mothballs, as they are toxic to bees and leave persistent residues in wax.
Cold storage. If you have access to a cold room or unheated building that stays below 4°C (40°F) through winter, storing comb there prevents wax moth activity entirely, since the lifecycle stalls below about 10°C.
What do you do if you find an active infestation?
In a living hive: remove the affected frames, shake or brush the bees off, and freeze the frames for 48 hours to kill all moth stages. Scrape away webbing and frass from the box walls. If the comb is severely damaged (collapsed cells, heavy tunneling), discard or melt it down for wax rather than returning it to the hive. Replace with clean frames of foundation and let the bees rebuild. If the colony is weak, investigate and fix the underlying cause (queenlessness, mite load, starvation) or combine it with a stronger hive, since a weak colony will simply get reinfested.
In stored equipment: freeze everything for 48 hours, clean the boxes, and switch to one of the long-term storage methods above. Any frames with intact comb can go back into service after freezing and airing. Having reliable pest-control products on hand before moth season reduces scrambling.
Do wax moths serve any useful purpose?
Surprisingly, yes. In nature, wax moths are the recyclers of abandoned bee colonies. When a feral colony dies in a tree cavity, wax moths consume the old comb, clearing the cavity for a future swarm to occupy. Without wax moths, old comb would accumulate indefinitely, and the disease spores and chemical residues it carries would persist. In a managed apiary, this ecological role is less welcome because we want to keep our comb and equipment intact, but it explains why wax moths are everywhere bees are: they evolved alongside honey bees as part of the same system.
What gear do you need for moth-related hive inspections?
Checking weak colonies, removing infested frames, and performing late-season inspections all require calm, protected work at the hive. At OZ Armour, we build gear for this kind of hands-on management. Our ventilated bee suits you can wear into the evening keep you protected during late inspections when moths are most active, and pairing them with beekeeping gloves tough enough for sticky, webbed frames and a beekeeping veil with a full, unblocked view gives you visibility while working through damaged comb. For quicker checks, a bee jacket that covers you without slowing you down and bee trousers that seal tight at the waist and ankle cover the job. Families inspecting together can put younger helpers in a kids' bee suit they will not outgrow in one season. A smoker and hive tool complete the kit.
Wax moths are not the catastrophe they look like when you first encounter them. They are a symptom of weakness, and they are preventable with strong colonies and proper comb storage. For the bigger picture on hive pests and diseases, our complete guide to bee diseases, pests, and treatments covers Varroa, foulbrood, Nosema, small hive beetle, and more. If you are just starting out, a 12-step path to becoming a beekeeper covers the foundations from first hive to first harvest.
Sources: Greater wax moth identification and lifecycle from LSU AgCenter (January 2024) and NSW Department of Primary Industries Primefact 658 (February 2023). Lifecycle duration (~6-7 weeks at 30°C) and cold-kill thresholds from UF IFAS Extension (Jack & Ellis, 2018, EDIS AA141). Storage control methods (freezing, Bt/Certan, PDB/Para-Moth) from Penn State Extension, Betterbee, and Carolina Honeybees. UK species data from APHA National Bee Unit (BeeBase). Ecological role of wax moths from Flow Hive and published entomological references.
