Controlling Wax Moths in Your Apiary

Controlling wax moths in your apiary

By Ronald Lindsay, 10/2016

One of the many concerns bee keepers have is controlling wax moths, both in their hives and in stored supers off of the hive. They can be an insidious pest. If you have experienced a complete infestation of wax moths in one of your supers you know what I mean. The super can be completely engulfed in a mass of cottony fibers, intertwined with pupa casings, moth droppings, and crawling larva. The comb is completely destroyed and any attempt to salvage the frame is generally useless. After cutting out the mess from the frame you find that even the frame has holes burrowed through it, along with grooves cut deep into the frame where the moths have produced cocoons. The general recommendation for this situation is to burn the frame, comb (what’s left) and all.

The following discussion is to fellow beekeepersthat are looking for methods to controlling wax moths in their supers, both on the hive and in storage. This is a collection of suggestions that I have found on the web. I am sure that some of these suggestions you will not like, or not be applicable for your situation. I will NOT be talking much about the life cycle of the wax moth. It maybe of interest to you, and some of the sources I looked at do go into a long discussion on the wax moth life cycle. If you are interested in that aspect, I encourage you to go to the web for that information. I will only bring it up in the context of controlling their populations.

Monitoring practices

Adult wax moths are normally present in most apiaries during warmer months. They are nocturnal and spend their daytime hidden in bushes, trees or other sheltered places. In early evening, the adult female moths fly and often sneak by guard bees, which have relaxed their protection duties. Weak colonies are not capable of protecting their colony entrance from intrusion by this pest, If adult wax moths are found in the hive during daytime hours, the colony is weak and is likely highly infested and demoralized.

Basic preventative measures:

Beekeepers should maintain strong and healthy colonies by practicing good colony management to help the bees defend against wax moths.
Beekeeper can reduce wax moth problems in stored combby making every effort to prevent brood production in honey supers. Brood production leaves behind small amounts of pollen and cast larval skins which are a more attractive food source than cells that have a history of just honey storage. Newly drawn wax comb where only honey was stored offers a high level of resistance to wax moths (Wm. Michael Hood Dept. of Entomology, Soils, and Plant Sciences Clemson University).
Michael Bush of Bush farms recommends that : “Never put supers, especially wet ones, in a warm place. Especially when you have the option to put them outside where they will freeze and the moths will die”. His practice is also to wait until late to harvest. “After harvest I can put the wets on the hives and wait for some warm days for them to clean them up and after they are done, pull them off and stack them with no fear of wax moths as the weather is now cold and there are no moths around. If I want to harvest early, then I’d put the wet boxes back on and not pull them off until after a hard freeze. The moths, in my part of the country, don’t really get going until about late July or August and I try to have all of that drawn comb back on the hives by mid June at the latest, where the bees can guard them. So, I have no moths in the combs during the honey season (June through September), because they are guarded by the bees. I have no moths in the combs from October to May because we get freezing weather now and then which kills the moths and the moth eggs. I have none from May to June because they moths haven’t built back up from winter yet. “
From “The bee works“: “With a little care wax moth can be outwitted and the damage they do can be prevented. First, the practice of top entrances should be examined, provided they have screening then there will be no problem. Leaving a big hole in the inner cover, then a badly fitting roof, is just asking for trouble. Or even worse those holes drilled in the top of boxes allowing the bees a second entrance are a real problem. Apart from pollen in the honey, a cold evening and the bees pull down and form a cluster leaving that entrance unguarded, easy pickings for the wax moth, as they will fly in cooler conditions than bees”. I understand what they are saying here but one must balance the need for adequate ventilation and to encourage increasing honey storage in the upper supers. You decide.

Mechanical control:Traps

There are currently no traps marketed specifically for wax moths. Currently, traps exist for a variety of other moths, using pheromones and other attractants, but not for wax moths. A number of sources do descibe how you can make your own homemade trap. The general instructions is to: “use a 2 liter clear soda bottle with lid secured. A 1.25 inch (3.2 cm) diameter hole should be cut in the side of the bottle just below the shoulder of the neck. The ingredients for the bottle trap include one cup white vinegar, one cup granulated sugar, one cup water, and one banana peel. The bottle should be set aside a few days until the contents begin to ferment after which the bottle should be suspended a few feet off the ground using wire or string making a noose opposite the side of the entrance hole. Wax moths adults will be attracted by the trap contents and will enter the bottle entrance and die because they are unable to escape.” (Wm. Michael Hood Dept. of Entomology, Soils, and Plant Sciences Clemson University). Other sources use a1” inch hole and ½ cup vinegar instead of 1 cup. One sourceclaims “ that this trap will even attract and kill the bald faced hornet”.

I tried this technique earlier in the summer but never saw any moths in the trap. Since it is generally recognized that wax moths prefer older comb that contains pollen and pupa cases, I plan on adding to the basic “recipe” with some older cells that contain pollen. Possibly this will make the slurry more appealing. Since the trap is designed to attract the moth and “not let them escape”, I also plan on making the “hole” by making 4 one inch slits in a star burst pattern and folding the corners into the bottle, hoping to help prevent the moths from exiting. What doI have to loose?

Environmental methods:

Wax moth damage is expected when honey-extracted comb is stored in dark, warm, or poorly ventilated places. Unprotected, wet supers are highly attractive to wax moths. From Wm. Michael Hood (Dept. of Entomology, Soils, and Plant Sciences Clemson University):“From experience, I have learned to never store freshly honey-extracted supers in tightly sealed trash bags, thinking that you have excluded all life stages of wax moths. Invariably, wax moth eggs or larvae show up unexpectedly in the equipment and the comb can be destroyed in a few weeks in a warm storage area. One exception is to freeze the comb, allow the comb to thaw in a wax moth free room till dry, then store the frames in tightly sealed bags.”
On the other hand, maximum use of light and ventilation is recommended to control wax moths. Beekeepers who have only a few colonies can easily take advantage of these two physical factors. A very effective and economical method of moth control can be achieved by storing supers of comb or individual frames of comb by wire from the roof or rafters of a room or attic which has good light and ventilation. If wax moths have already become established and webbing is present in the comb, the use of light and ventilation option of wax moth control is not recommended. (Wm. Michael Hood Dept. of Entomology, Soils, and Plant Sciences Clemson University)
By KhalilHamdan(Apeldoorn, from the Netherlands)claims that some beekeepers in the UK protect their combs by wrapping them in newspaper. “Which the moths dislike its smell, this is done as soon as combs are removed from the hives. This method has been claimed to give good results.”
Cold Treatment: One of the best methods recommended by many articles is to freeze the supers to kill both the larva and eggs.Theminimum cold temperature storage time required to kill all life stages of wax moths in honey-extracted comb include: 20ºF (-7ºC) for 4.5 hours, 10ºF (-12ºC) for three hours, or 5ºF (-15ºC) for two hours. Additional time should be given for equipment to reach required minimum temperatures, especially in hot weather or large capacity freezers. These temperature exposure periods will have to be increased to kill wax moth larvae in comb honey. Wax moth development is accelerated at higher temperatures, so comb honey should be protected from this pest beginning immediately after harvest.(Agriculture Victoria: Wax Moth - A Pest of Combs and Honey Bee Products Note Number: AG1101 Published: April 2003 Updated: April 2009) “After freezing, the combs should be stored in a moth-proof environment to prevent re-infestation.Sealed, strong plastic garbage bags provide a good insect-proof storage environment.Combs that have been frozen and then placed in untreated supers for storage are immediately at risk to infestation because the supers may contain wax moth eggs. It is best to treat the super and combs and then place them together in a sealed plastic bag.” For some beekeepers this is a terrific method of treating for wax moths. No chemicals!If a large freezer is available, you are able to freeze large numbers of supers quickly and efficiently. Other beekeepers may want to consider purchasing a small chest freezer. But if you are like me, my freezer is filled with food and my wife would not appreciate filling if with frames to freeze and even if I could, I would only beable to freeze a few at a time.

A reminder from “Brushy Mountain”: “If you make cut comb honey it is necessary to freeze your comb for at least 2 days, this will kill the eggs and prevent them from hatching inside the packaging.”

Chemical methods:

Use of Dichlorobenzene

The use of dichlorobenzene seems to be pretty controversial. From British Beekeepers association publication (2012): “A treatment which was in common use and advised in olderbooks but is no longer acceptable is the use of para dichlorobenzene (PDB) crystals. This moth deterrent was extremely effective but the chemical can accumulate in the wax and possibly damage bee larvae and contaminate honey. This productshould not be sold or used. Similarly, no household moth killeror moth balls should ever be used as they are all based onchemicals that are highly toxic to bees as well as moths and, aswith PDB, can accumulate in wax and possibly contaminate honey”. Michael Bush, of Bush Farms says “What I would not do, and is at the top of my list of things not to do, is use moth balls, particularly the Naphthalene ones. Slightly better, and on the FDA list as approved, is PDB (Para Dichlorobenzene). But both of these are carcinogens and I have no use for such things in my food supply, and beehives are part of my food supply”.

And yet it is a practice that is accepted by FDA, used by many bee keepers, promoted by many apiary suppliers and seen as an acceptable practice by many other “experts”.

Michael Hood, Dept. of Entomology, Soils, and Plant Sciences, Clemson University says: “The use of chemicals in an integrated pest management program is recommended as a last resort when other options have failed or are not possible.” He accepts the practice and understands that it maybe necessary, but if you choose to use PDB there are a number of limitations or safeguards that he and others spell out that you should be aware of.

A.PDB is registered for wax moth control for use in protecting stored comb.

B.PDB cannot be used for wax moth control in live bee colonies, it will kill your bees.

C.It is NOT approved for protection of comb honey. Honey readily absorbs PCB fumes resulting in honey being unfit for human consumption. Combs that have been extracted need to be returned to the colonies to clean them from the remaining honey. Combs should be free of honey prior to treatment with PDB.

D.Beekeepers are strongly advised to air out stored chemically exposed supers for a day or two away from PDB prior to placement on colonies because it is toxic to bees at high concentrations. (or longer)

E.Mothballs which contain naphthalene are not registered for wax moth control and are illegal for use in protecting beekeeping equipment. Naphthalene is lipophilic (loves oil) and will permeate the wax. It will also kill bees. It is not an approved treatment (and never has been).

If you choose to use Dichlorobenzene:

Five full-depth supers or 10 half-depth supers can be stacked vertically in beehive fashion making sure to secure any cracks or openings with tape to provide a good seal. The product label calls for 3 oz or 4 tablespoons (85 g) to be placed on a piece of paper or cardboard on frame top bars of the top super with lid to cover the stack. Some beekeeping equipment suppliers sell a hive shim that contains a sliding drawer which crystals can be conveniently placed and inspected. As the crystals vaporize, the vapors are heavier than air causing the vapors to move downward through the stacked supers killing wax moth adults, larvae, and pupae. PDB vapors also repel wax moths from entering exposed equipment. However, the vapors will not kill wax moth eggs. Crystals vaporize quickly at warm temperatures and have to be replenished periodically.

Dichlorbenzene can be purchased from Dadant, Brushy Mountain, and Mann Lake. It is usually sold as “Paramoth”, but you also can buy it at Wal-mart. Look for “Moth ICE Crystal”, (cost: $4.40 per pound) NOT moth balls. Read the label carefully, if it says Napthalein DO NOT USE IT! You may have a hard time finding the moth cryatals. Wal-mart stocks some things in two different places. This is one of them. If you find the Moth ICE crystals with Dicholorbenzene it is the exact chemical used in Paramoth.

I have used PDB in the past, but after doing this research I know that I will reduce (not eliminate) the use of PDB. My plan is to use PDB in the late summer, early fall (if needed) to get my supers through the peak of the wax moth “season”. Then with the advent of the cold weather remove any PDB on the hives if there is any left. Allow the hives to “air out” during the winter and early spring so that not residual vapours remain prior to putting them back on the hives.

2.Use of Acetic acid

Acetic acid is the active ingredient in vinegar. But vinegar is about 3%, this method uses 80%. Acetic acid (also known as “glacial acid) and can be used for controlling wax moth in stored combs and for cleaning combs from Nosema spores. Fumigation with acetic acid will kill moths and their eggs and larvae. After the honey is extracted, boxes of combs are piled in stacks, no more than five high. The seams between the boxes are taped with tape to form an air tight seal. A wad of cotton wool 15 by15 cm or similar absorbent material soaked in 80% acid is placed on top of the uppermost frames in the stack before the lid is sealed, using 25 mills 80% acetic acid per box in the stack. The top of the stack is covered with an inner and outer cover and the stack is left undisturbed for two weeks. The fumigation can be repeated at intervals of 2-3 weeks. Acetic acid is not a very strong acid when it is in vinegar, but at 80% it must be handled with caution to avoid splashing the liquid on the hands or on the face or into the eyes. Splashes on the hands should be washed off immediately. After fumigation the boxes of combs should be aired for about two days before they are used.

What is nice about acetic acid is it is a natural product, not even remotely carcinogenic but may not be readily available. I do not know if any product in the local area that is 80 % acetic acid. It would be available from chemical supply stores and off the Internet, but shipping costs maybe high.

Biological methods:

Use of the bacterium“Bacillus thuringiensis”.

In Organic gardening, certain species of bacterial are used to control insect pests. BUT, not all bacteria are the same. The bacteria usually used in organic gardening is Bacillus thuringiensis subspecies kurstaki , marketed as: “BtK”. BUT, Bacillus thuringiensissubspecies aizawai (BkA, many times referred to as: B401) is manufactured specifically for wax moth control in stored comb. The material is formulated to kill young wax moth larvae as they attempt to feed on comb and must be used as a preventive before combs are infested. B401 (BkA) leaves no residue on comb and it is harmless to bees and humans. Some other strains of Bacillus thuringiensis (BtK) are toxic to bees and humans, so beekeepers must resist the temptation of using other BT products. Do not use the Bacillus thuringiensis subspecies kurstaki , or “BtK”, use the subspecies aizawai,. It is harder to find. B401was marketed in the US several years ago by the trade name Certan®. Certan used to be approved for use on wax moths in the US but the certification ran out and there was no money in renewing it, so it’s no longer labeled that way in the US, but is available for that use from Canada, it was reregistered and approved for sale in Canada, effective May 2015. It is available for use against moth larvae (but not wax moth per se) in the US as Xentari. The directions calls for a mixture of one part Certan® (or Xentari) to 19 parts water to be sprayed on both sides of every frame for effective wax moth control. Once mixed the solution must be used the same day. One application of the product gives wax moth protection in stored comb until the next season. It can be mixed with water and sprayed on the comb with a garden pressure sprayer. This is the only biological larvaecide available for wax moth control, it has no effect on you, your honey, bees or wax. Used just before storage or before the comb is placed on the hive it is ingested by the larvae and kills from the inside out.. It can be sprayed on infested combs even with the bees on them to clear up the infestation. It can be sprayed on foundation before putting it in the hive. It can be sprayed on combs before storing them. One possible source for BtA is: It is marketed as Xen-tariand a one pound bag is $40 As of 10/2016 can buy a 5 pound bag of Xen-tari on Amazon but at a cost of $105