Dr. James E. Tew
E-mail Tew.1@osu.edu
The greater wax moth is grayish-brown, about 0.75 inch long and has a wing spread of 1.25 inches. The larvae can destroy wax combs in storage or in weak bee colonies by tunneling in the wax. The best control of wax moth larvae in apiaries is to maintain strong colonies. To protect empty wax comb in storage, chemical or nonchemical control can be used.
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Currently, the only chemical available for controlling the wax moth is the moth crystal, 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 70°F. 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.
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 115°F (46°C) for 80 minutes or a temperature of 120°F (49°C) 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 120°F (49°C). 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 |
|---|---|
| 20°F (-7°C) | 4.5 |
| 10°F (-12°C) | 3.0 |
| 5°F (-15°C) | 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 60°F. Monthly inspections are especially important in Ohio where wax moths are present in warm months.
Produced in cooperation with the Department of Entomology, Auburn University
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Keith L. Smith, Associate Vice President for Ag. Adm. and Director, OSU Extension.
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