Greater Wax Moths


The state apiary inspector got me into wax moth production. Not directly, but one must fix blame. I had decided that replacing two frames per hive body per year made sense as a way to reduce disease pressure. Having done this with 36 hive bodies, I now had 72 frames of old wax. I was going to destroy it, but Charlie said to melt it down, he would buy it. Now my solar wax melter only holds only 6 frames and it was my plan to put 6 new ones in each time, I remembered it. I don't remember so well. Anyway, I stacked the others up in an abandoned barn over the summer. Well, as you can see from this photo, I got into wax moth production in a big way.

Now I have never had a problem with wax moths in my hives. I have never had a problem in my stacked supers either. In the supers that aren't used, I have always kept a plastic lid and Parachlorodibenzyne balls. I have refilled these pretty faithfully twice during the summer. In Nebraska we have cold winters that pretty much solve the problem of storage for used equipment.

Of all moths, the Greater Wax Moth, Galleria mellonella, causes the greatest damage in apiaries that lead to material and financial losses every year. You will read over and over that wax moths don't kill colonies, a strong queenright colony can defend itself against wax moth problems. Finding a colony looking like the above photo is a sign that something else happened, then the wax moths moved in to "clean up". They build silk-lined feeding tunnels, which is the gray mess you see.

The adult wax moths causes no damage because their mouthparts are atrophied. Wax moths do not feed during their adult life. The larvae feed, destroy combs and damage your woodenware. Notice the little pits in the wood box. Each cocoon lies in a pit and although this probably doesn't harm this box, the pits in your frames certainly weaken them.

Adult wax moths and larvae can transfer pathogens of serious bee diseases. In colonies infested with foulbrood, the feces of wax moths contain large amounts of Paenibacillus larvae spores. Wax moth's move from hive to hive and thus may be a vector for the transfer of brood disease.

The female adult lays eggs in the cracks within the hive. The newly hatched larvae feed initially on the bottom board's fragments. As they grow they move onto the frames of comb and feed on pollen, honey and wax. They build a web of silk pathways. A single larvae will also tunnel beneath the wax cappings and you see a streak of damaged cells.

Everywhere they feed they lay down silken webs. The bees generally move away from the areas the larvae are feeding and may abandon the hive entirely. The loss of pollen also further weakens the hive. The larva feed in particular on impurities occurring in wax, such as feces and the cocoons of bee larvae as well as pollen. It was found that larvae feed pure wax don't develop. I think this explains why they don't bother my stacked unused supers. I do use queen excluders so there hasn't been any brood reared in my supers.

Wax moth development goes through stages--egg, larva and pupa. The sequence is interrupted when the hive temperature is too low or when there is no food. Therefore, the cycle can last between 6 weeks and 6 months depending on the temperature. At the end of the larval stage, the larva spins a silk cocoon on the wooden frames or hive walls. Notice after I scraped the cocoon away, the larva have spun the cocoon in a hollow it had bored into the wood. In the cocoon, the larva changes into a pupa and then into the adult moth. This metamorphoses can last from one to 9 weeks. After they immerge, the adult females begin laying eggs in 4 days. They will try to enter the hive, but if the hive is strong, they aren't allowed to enter and they lay in the cracks on the outside of the hive.

The basic rule of wax moth control is to maintain strong queenright colonies. In Nebraska the cold winters kill the wax month in our stored used equipment. If you must store unused equipment over the summer, you need to treat. The primary method of treatment is paradichiorobenzene (PDCB), mothballs. When you buy this check that its PDCB and not naphthalene based mothballs. Recently I stopped at discount store and found PDCB and naphthalene mothballs, both in similar looking blue packages like the one shown. PDCB is put above the hives since the mothballs melt quickly and their gas is heavier than air. You must also air the hive bodies out a couple days prior to use or the bees may leave you.

PDCB is highly volatile and lipophilic (easily soluble in fat and wax) substance. Beeswax can take up this material and a part of it may later migrate into honey. The longe you have PDCB on the stored hives, the more is taken up into the wax so you need to minimize this use. We all know how mothballs smell and we certainly don't associate this chemical with the purest of foods, honey. It is recommended that alternative control strategies be employed. My friend, Lee Rents, hangs fly strips all over the storage room. They are covered by moths and flies. He told me each moth he caught was one less to lay eggs in his hives. This makes sense.

Recently in sci.agriculture.beekeeping, people have been discussing a trap. I made these last year and use them ( also hung fly strips, they are cheap). I use a 2 liter plastic pop bottle. Cut 2 quarter sized holes opposite each other just before the taper for the bottle's neck. Put 1 cup vinegar, 1 cup sugar, 1 banana peel fill up to about 2" from holes with water. I just set them on the stored hives, but you can also hang by a string. They are also pretty good for catching wasps! . It takes a week or two for the mixture to "pickle" enough to attract the moths.

I would like to hear from anyone using acetic acid (white vinegar) fumes. Acetic acid vapor instantly kills eggs and moths. The larva, especially in the cocoon, is more resistant and must be exposed to the vapors for longer.

In "The Hive and the Honey Bee" under the heading "Wax moth" you'll find mention of a produce called Certan, which was a beneficial organism, Bt, that was also approved for use as a honey comb fumigant. The manufacturer, unfortunately, took it off the U.S. market. It can still be purchased though in the U.S., beeworks. I have never tried this, myself. If you do encounter wax moths in a seaming strong hive, the best approach is to lessen the numbers and give the bees
a fighting chance. Shake the bees off a comb and while holding one end of the frame, whack the bottom bar or top bar of the other end sharply several times with your hive tool. The vibration causes worms of all sizes (except those in cocoons) crawl to the surface so they can be destroyed. Change ends a couple of times and repeat. It may surprise you to see how many worms emerge. Don't worry about the web, the bees can take care of that better than you can.
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