Greater Wax Moth

 

Where did wax moths come from?
Wax moths are thought to originate from Asia. Wax moths now inhabit much of the world today and are thought to be found in every honey bee colony world wide.

What are wax moths and what can I do to control them?
The Greater Wax moth (Galleria mellonia L.) are 1/2 to 3/4 inches long and grayish in color. The female wax moth deposits her eggs in the cracks and other places inside the hive. Thus after hatching, the larvae if not removed from the hive by house bees can destroy a hive that is in a weaken or stressed state.

The larvae grows to about an inch length and causes the most damage to a hive at this stage. As they tunnel through hives they make trails of web like strands and attach themselves to frames and hive body parts to spin cocoons just before they pupate. This attaching causes holes and deep burros in frames and hive body parts. They seem to prefer the dark wax of the brood comb. This comb contains bee larvae exoskeletons and small amounts of pollen which are said to attract the wax moth larvae. The only true preventive measure to help insure that you do not get a large infestation of wax moths is to have a good strong health colony.

Symptoms of wax moths:
1. Live larvae (wax worm) and webbed like tunnels in combs.
2. Cocoons attached to wooden parts of frames and hive body.
3. Destroyed comb.

Why do they occur in bee hives?
Wax moths generally take over hives that are in a weaken or stressed condition. Lack of queen, an older queen or heavy mite infestation are usually the main reasons why a hive becomes weaken or stressed.

 

Chemical Control

Paradichlorobenzene (PDB)

To use PDB, place no more than five deep supers or ten shallow supers in a stack. Seal the cracks between the supers with masking tape or similar material. The stack of supers should be placed on several thicknesses of newspaper or a solid, smooth surface so that the gas cannot escape at the bottom of the stack. Place a piece of paper or cardboard 6 inches square near the center on the top bars in the top super. Put 6 tablespoons (3 ounces) of PDB crystals on this piece of paper. Then put the cover tightly in place. Check each stack every 2 or 3 weeks to be sure that the PDB crystals are still present. If crystals are no longer present, add more.

PDB is most effective at temperatures above 70F. A few days before you are ready to use the supers, hive bodies, or combs, remove them from the stack and set them on end so they can air out.

WARNING: PDB can be injurious to man and animals if used improperly. Follow directions and heed all precautions on container label. DO NOT use PDB on honeycombs containing honey intended for human use.

Phosphine

Although phosphine (Phostoxin, Gastion, Celphide, Alphos Detia and Fumitoxin) will kill at all stages of the wax-moth life cycle, reinfestation can occur in stored equipment if it is not securely sealed. Fumigate equipment out in the open when a gentle breeze is blowing towards an uninhabited area. No combs removed for storage should contain honey. Place these combs in supers in separate stacks up to five high. Each stack should have as a base a sheet of PVC (plastic) 0.25 mm thick or heavier. Fold up the edges of the PVC sheet and seal with PVC tape or clips. Securely seal all joints and cracks between the boxes. Place one tablet in a container (to catch residue) on the top bars of the frames in the top box. Cover the stack with a lid of PVC sheeting and seal with PVC tape.

After seven days, the wax-moths should be dead. If boxes are moved to a storage area, each stack must be resealed to prevent entry of adult moths. Check regularly for signs of reinfestation particularly during summer. All treated equipment must be ventilated thoroughly before use. This should be carried out in the open by allowing air to circulate through the equipment for five days.

Warning: Prominently display poison notices in the fumigation area throughout the exposure and ventilation periods and on all doors leading into rooms where boxes are stored. Phosphine is toxic to all forms of animal life. Avoid inhaling. Suitable gas respirators must be on hand when phosphine tablets are being used.

Respirators must be fitted with a canister for phosphine and properly maintained, as they have a limited life. Gloves of plastic or synthetic rubber should be worn when handling phosphine tablets. Open tins in open air. Seal unused tablets in tins with flexible PVC tape. Phosphine tablets may explode on contact with water. Bury tablet remains.

 

Non-Chemical Control

Temperature extremes can be used as a non-chemical control measure for wax moth control.

Heat. All states of the greater wax moth are killed at a temperature of 115F (46C) for 80 minutes or a temperature of 120F (49C) for 40 minutes. Be sure to allow combs to reach the required temperature before measuring the exposure time.

WARNING: Be careful not to expose honey combs to temperatures in excess of 120F (49C). Heat-treat only those combs having very little or no honey (combs softened at high temperatures may sag and become distorted). Heat-treat supers of combs only when they are in the normal, upright position. Provide adequate air circulation for the heat to be evenly distributed throughout the comb. Ventilating fans are useful for this purpose. Turn the heat off and allow combs to cool before moving the supers.

Cold. Wax moths are also killed by low temperatures. The use of low temperatures can prevent the sagging problem which sometimes occurs when combs are treated with heat. Combs with honey and pollen can be treated by use of low temperatures without much danger to the combs.

WARNING: Very cold honey combs are very brittle. The minimum temperature and exposure time needed to destroy all stages of the greater wax moth are shown in the following table.


 

Temperature Time In Hours
20F (-7C) 4.5
10F (-12C) 3.0
5F (-15C) 2.0

Once the combs are treated, store them where no adult wax moths can get to them. Inspect combs monthly for any signs of infestation, especially if temperatures rise above 60F.

Carbon dioxide

Carbon dioxide (CO2) at concentrations above 95% can effectively control wax-moth. For further information see Morse, R. A., 1978, Honey Bee Pests Predators and Diseases. Cornell University Press, London.

Trap

Take a 2 liter plastic coke bottle and drill a 1 inch hole just below the slope on the neck, then add 1 cup water, 1 cup sugar, cup vinegar and finally 1 banana peel. Wait a few days till it starts to ferment, then tie it into a tree close to the hives. This trap will draw the wax moth, they enter the hole can't get out and drown in the liquid.

 

Photo credit: H. A. Turney

Photo from www.beekeeping.com

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Information contained on this page is provided as general advice only. For application to specific circumstances, professional advice should be sought.  Readers should ensure that they make appropriate inquiries to determine whether new information is available on the particular subject matter.

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