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Protecting Comb in Storage
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Treatment Against Waxmoth
and general sterilisation of honey comb

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Total control is unlikely to be achieved, the strength and health of the bees themselves is the best starting point. It is quite normal to find an occasional adult waxmoth or a few larvae in an active hive.

Hives that have weak colonies, or too many combs for the amount of bees to cover are ideal places for wax moths to get a stronger foothold, in which case the quantity of adults and larvae found will increase, along with the evidence of damage.

Good beekeeping practice including scraping of burr comb and propolis from hive and frame woodwork will reduce the opportunity for wax moths of either species to become established.

Combs in storage are ideal breeding grounds for waxmoths. Drawn comb is a magnet for eggs to be laid in or on or just close to. Warm storage temperatures also accelerate the destruction process. If you intend to store comb out of the hive, you must protect it in some way.

'Wet' storage of extracted comb has some merit from a moth control/avoidance point of view, instead of returning extracted supers to the bees for cleaning up, they are left with the small residue of honey that exists after extraction. I have personally done this successfully, but it causes a second set of problems in that any crystalised honey already in the comb when they are used again next season will seed early crystallisation of the subsequent crop. Furthermore any cells around the fringes of the comb that contained honey that was not fully evaporated may have fermentation occur in the residue, which can cause dysentery when the combs are returned to the bees.

Irradiation with gamma rays will kill all developmental stages including eggs, but costs are high and you still have to find a suitable storage container, that is totally moth proof, to house the combs after they have been sterilised.

Various fumigation methods can be used, but care must be taken that no remnants of fumigant are left impregnated in the wax. And of course adequate precautions must be taken to avoid inhalation of the fumes by human operators. I can also mention here two methods that I myself am not familiar with, but others may wish to follow up... Ethylene oxide, and Phostoxin (the latter in Australia) have been used for this purpose.

Acetic acid fumes have an effect and the method of use is the same as for pdb crystals, but the saucer is filled with 80% acetic acid instead of crystals. The acid is very corrosive and will attack metal fittings and fasteners. This kills the egg stage as well as all others and is useful to sterilise against Nosema spores.

Sulphur dioxide SO2 has been used, methyl bromide fumigation is offered by contractors, but it requires comb storage rooms that are completely moth tight. I believe this method gives protection against many diseases of bees as well as wax moth infestation.
Para Moth Balls
Naphathlene (moth balls) are sold for protection against the clothes moth. Some sources say that they are not effective against waxmoth, but I have had several reports from individuals that have used them and claim success. I have used them in cupboards indoors to store frames fitted with foundation or starter strips. The few larvae that I have found in these cupboards were dead, but that could be the lack of protein available, just as easily as action by napthalene.

Paradichlorobenzene (PDB) can be obtained as loose crystals, in bucket sized quantities, from the appliance trade or occasionally at hardware stores. It sublimes to a gaseous state above 20°C, the gas itself is heavier than air. It does not kill waxmoth eggs and you need to be sure you have a continuous fumigation in areas subjected to high ambient temperatures as the crystals may evaporate entirely. Beeswax comb will absorb the smell of PDB, see the page 'Combs that smelled of PDB', you should air combs very thoroughly after storage before using them on bee colonies and particularly if you are intend to hive swarms on them.

Build a stack of hive boxes until it is 2 Metres (six feet) tall and tape over the joints with parcel tape. Place 100 gm of PDB crystals on a saucer that is resting on the frame top bars in the topmost box. Or they can also be put in a paper envelope and fitted to the inside of the box at the top of the stack with a drawing pin (thumbtack). If the ambient temperature is high, the crystals may need replacing.

PDB is not suitable for fumigating capped honey or sections.

Carbon Dioxide (CO2) can be used to exclude air, from comb honey that is intended for sale as well as for storing drawn comb in sealed containers or comb cupboards.

Heat... This needs close temperature regulation ( -0°, +2°) and the air needs to be circulated in the enclosure by several small fans to ensure even-ness of temperature distribution. 47°C for 85 minutes is required.

Freezing can be used for comb honey or empty combs of any type -15°C to -20°C for 72 hours is my 'belt and braces' recommendation, but I have seen shorter times and higher temperatures quoted. If empty comb is used and the cold air is rapidly circulated by fans, much shorter times, say 5 or 6 hours can be used.

Bacillus Thuringenisis (BT)(Certan®) is available in UK and is a microbial bacteria that can kept alive by culturing in milk after macerating affected larvae.

DIY Moth traps will help, but will not give total control.

Biological Control... Trichogramma wasps that are used commercially in green houses will control wax moth larvae, but they have to reach a particular size before the wasps will parasitise them, so some damage to combs is inevitable before control is gained.

This post was made by David Brandon to a discussion group...
"I have found that by placing a layer of tobacco leaves between boxes of brood comb (in storage) and placing a lid on top, I no longer have problems with wax moth."
Percussive shock... I heard a story from an old timer that said waxmoth were susceptible to the sharp blast of pressure caused by firing a blank starting pistol inside a hive body. I tried this out on the occasion covered in the bucket of waxmoth saga. I used .22 rimfire blanks and 9 mm black powder blanks. Both sizes caused a few adult moths to fall out of the boxes stone dead with their legs in the air. When I tried this I did not have the presence of mind to fire duplicate shots in the same box or to fire a 9 mm after firing a .22. Although this appears to work it is not cost effective and is time consuming.

Dessicating atmosphere... It is thought that wax moth eggs need a moist atmosphere to hatch. Therefore the addition of dessicants to the various methods would probably improve them as treatment against the waxmoth.

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