Wax moths are the vultures of the beekeeping world — they do not kill healthy colonies, but they feast magnificently on the dead and dying. And robbing? Robbing is what happens when your bees' neighbors decide that stealing is easier than foraging. Both are problems of weakness, opportunity, and — if we are honest — sometimes beekeeper error.
Let us address them in turn, for though they are different threats, the solutions overlap in elegant ways.
There are two species you will encounter: Galleria mellonella, the Greater Wax Moth, and Achroia grisella, the Lesser Wax Moth. The Greater is larger, more destructive, and more common. The Lesser is smaller, less aggressive, but still a nuisance. Both are night fliers — drab, gray-brown creatures that slip into hives after dark, evading the guard bees' watch.
The adult moths do no damage. They do not even eat — they live only to mate and lay eggs. It is the larvae that wreak havoc.
A female moth enters the hive, seeks out dark, unguarded comb, and lays her eggs — sometimes hundreds of them — in crevices. The eggs hatch in about a week, and the larvae begin tunneling through the comb, feeding on wax, pollen, bee cocoons, and any bits of propolis they encounter.
As they tunnel, they spin silk threads behind them, creating a webbing that binds the comb together in a tangled, filthy mess. Advanced infestations look like something from a horror film: frames encased in gray silk, comb reduced to crumbling debris, the smell of decay hanging in the air. You will see the larvae themselves — fat, cream-colored grubs with brown heads — wriggling through the wreckage.
The cycle from egg to adult moth takes about six weeks in warm weather, faster in heat, slower in cold. In the southern United States, wax moths can produce multiple generations per year. In the north, they may overwinter as larvae, pupating in spring.
Here is what every beekeeper must understand: wax moths only destroy weak or abandoned colonies. A strong, populous hive will patrol every frame, chase moths away, and remove larvae before they can establish. Guard bees at the entrance intercept moths attempting to enter. Nurse bees inside the hive clean up any eggs that slip through.
If you open a hive and find significant wax moth damage, the moths are not the problem. They are the symptom. The problem is colony weakness — low population, failing queen, starvation, disease, or some combination thereof. The moths merely exploited the opportunity.
Your first response to wax moth infestation, therefore, should be to ask: Why was this colony too weak to defend itself?
The real wax moth battles are fought not in active hives, but in stored frames. Pull a honey super for winter storage, stack it in your garage, and forget about it — by spring, it will be a moth nursery. Prevention here is straightforward:
Freeze frames for 48 hours immediately after removal. This kills any eggs or larvae present. Then store frames in a sealed, well-lit space with good air circulation. Wax moths hate light and moving air.
Use Bacillus thuringiensis (Bt), a biological larvicide sold as Certan. Spray it lightly on stored comb. It kills wax moth larvae without harming bees. Reapply yearly.
Paradichlorobenzene (PDB) — the active ingredient in moth crystals — can be used to fumigate stored equipment. Place crystals on newspaper atop stacked supers, seal with a lid, and let the fumes do their work. The crystals sublimate (turn directly from solid to gas), killing moths and larvae. Remove the crystals and air out equipment thoroughly before returning it to bees, as PDB is toxic to them in high concentrations.
Robbing is exactly what it sounds like: bees from one colony invading another to steal honey. It is vicious, chaotic, and surprisingly common during nectar dearths — those frustrating periods in mid-summer or early fall when little is blooming and bees are desperate for food.
A strong colony can defend itself. A weak colony cannot. The robbers overwhelm the guards, pour inside, gorge on honey, and fly home. They return with reinforcements. Soon dozens, then hundreds of robbing bees are pillaging the hive. The defending colony's population plummets as bees die in combat. The stress can cause the colony to abscond or collapse entirely.
How do you tell robbing from normal foraging? Watch the entrance:
If you see these signs, act immediately. Robbing can escalate from minor skirmish to colony collapse in a matter of hours.
Reduce the entrance. Install an entrance reducer to give guard bees less space to defend. One or two bee-widths is sufficient during a dearth. Robbers cannot overwhelm a narrow entrance as easily as a wide one.
Do not spill syrup or honey. A single drop on the landing board or outside the hive is like ringing a dinner bell. Feed inside the hive, not outside. Clean up spills immediately.
Inspect quickly during dearths. The longer a hive is open, the more its scent spreads, attracting robbers. On high-risk days, conduct only essential inspections, work fast, and close up promptly.
If robbing has started, close the hive completely — stuff the entrance with grass or burlap, drape a wet sheet over the entire hive to confuse the robbers, and leave it for 24 hours. This breaks the robbers' orientation. When you reopen, use a reducer and monitor closely.
"A beekeeper who prevents robbing is worth ten who try to stop it once it has begun."
— Vintage beekeeping maxim
Wax moths and robbing share a common theme: they exploit weakness. The solution is not to wage endless war against these pests, but to keep your colonies strong. Well-fed, populous hives with young, vigorous queens shrug off both threats with ease.
When you find a colony overwhelmed by moths or robbers, do not curse the pests. Ask yourself: What made this colony vulnerable? Address that, and the pests become irrelevant.