Certan (B402) Wax Moth Prevention

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Beekeepers strive to protect honey bee colonies from a plethora of pests. Not only do some pests harm or even kill entire hives – they also ruin valuable resources. One common example is the damage caused by wax moth larvae-if left unchecked. Many frames of valuable drawn comb can be destroyed in a few short weeks. One natural way of preventing larva damage is to use B402 Certan for wax moth prevention.

Empty frame with good drawn out comb and a bottle of certan wax moth preventative.

Moth damage happens in live hives too-in certain situations. But, it is the loss of valuable drawn comb in stored honey supers that is most frustrating and easier to solve. This is just another facet of beehive management that every beekeeper needs to consider.

B402 Certan: An Overview

Known among beekeeper circles as “Certan”, the product is sold today as B402 (Certan) in the United States and B401 (Certan) in other parts of the world where available.

It is a preventative against wax moth damage in the honeycomb of beehives. Safe and environmentally friendly, it consists of a concentrated solution of Bacillus thuringiensis.

This form of Bt is a subspecies of aizawai that is harmless to humans and honey bees. It is very effective against Galleria mellonella (Wax Moths).

Thankfully, it leaves no residue in beeswax or honey and is even suitable for organic farming operations.

Years ago, Certan was available as a reliable way to prevent comb destruction. Then it was off the market for a while – in recent years, Certan received approval from the EPA for use by beekeepers again.


This is a liquid product that contains spores of Bt and must be diluted in water to a 5% solution. It is important to shake the bottle well before mixing and shake the sprayer well during application. Treatment solution should be used within 24 hours of mixing to maintain effectiveness.

B402 Certan is mixed with water and the solution is used to lightly spray each side of the comb surface.

The manufacturer (Vita-Health) maintains that a 5 oz bottle of B402 Certan will treat approximately ( enough to treat 100 deep frames, 150 medium frames, or 200 shallow frames).

Frame of stored drawn comb showing signs of wax moth larvae damage. Webbing and frass visible.

Timing of Application

The most common time to apply Certan is after you complete the honey harvest. After empty frames of comb are removed from the honey extractor and allowed to dry – it is time to spray them before storage.

This application kills young wax moth larvae. It is a preventative to use before damage occurs.

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A single application gives good results that last though the next season. I have had excellent results with some sprayed combs being protected beyond a year.

Listed materials needed to make and use certan B402 spray for wax moth prevention.

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The materials needed to spray your comb with B402 Certan and protect your valuable comb are mostly common household items. You need the product (available at Bee suppliers or buy Certan online) some measuring tools, a good sprayer and a container with a lid.

Application of B402 Certan on Drawn Comb

I am sharing with you MY method for using this product. Always read and follow the manufacturer’s instructions – they are your best guide for legal use of the product.

Gather your materials and have the frames with comb ready to spray. My honey frames have been removed from the extractor and cleaned of any honey residue by the bees – they are now dry.

Small glass jar with lid, 1 cup measuring cup, 1 teaspoon measuring spoon and bottle of B402.

We are going to make a small recipe – you have double it for larger amounts of solution. However, keep in mind that you need to use it within 24 hours.

To make 2 cups of spray, I use a pint jar with a lid. You will need a teaspoon measure and 1 cup measure.

Steps 1 thru four of making a 5% solution mix of certan and water.

If this is your first time opening the bottle-you will find a foil seal. Shake the product vigorously and then remove the seal.

Use your measuring cup to put 2 cups of water in the pint jar.

Use a measuring spoon to put approximately 4.8 (almost 5) teaspoons of B402 Certan into the jar of water.

After placing a lid on the jar, shake, shake, shake to completely mix the water and solution together.

Spraying frames of honeycomb with wax moth larva preventative.

Pour your mixture into a good quality spray bottle. Cheaper sprayers will work but they are unreliable and may result in loosing some of your product. Test your sprayer with water before adding the Bt mixture.

Lightly but thoroughly spray each side of the honeycomb in your frames. You want good coverage but do not try to fill the wax cells with water- just a nice mist over all the surface.

Frames of comb drying in sun after being sprayed with certan wax moth preventative.

Then, place the sprayed frames of comb in the sun or any place with good air flow and allow them to dry completely. Once dry, they are ready to store in whichever manner you choose.

Expert Tips

Although a wonderful fit for stored honey super frames, this preventative can be applied to any frames from the hive.

Any honeycomb that has had brood reared in it is more attractive to moth larvae. For instance, maybe you use queen excluders to try to prevent brood cells being in your honey supers.

But, if you forget to put them on in time – you may end up with a little brood there. This makes the comb darker and more attractive to moths. Be sure to spray these areas well with your Bt spray.

Used frame of wax drawn comb with area previously used for brood cells.

Only mix as much solution as you can use in a day. It is much better to have to mix twice rather than fail to have your comb protected by using old “dead” protection.

You can buy agricultural forms of aizawai Bt to use. However, they are usually in granular form not liquid and are not labeled for use in beehives.

Heavy damage of comb by moth larvae too late to treat.

When it is Too Late for Preventative

A strong colony can repair a small amount of moth larvae damage. However, there comes a point when it is too little too late for preventative treatments.

If your frames and full of webbing, frass and other signs of damage, it is time to install new beeswax foundation and too late for treatment. Your colonies effort will be better spent building out new comb rather than trying to replace a mess.

This is another reason it is important to practice good wax moth treatment plans early – keeping your hives populous and able to protect comb in the hive.


What is B402 Certan, and why is it used for wax moth control?

B402 Certan is a registered product that uses Bacillus thuringiensis, a subspecies of aizawai to control wax moths in honeycomb. It is natural and not harmful to humans or honey bees.

Can I use B402 Certan on frames with brood cells or darker comb?

Yes, B402 Certan can be used on any frames from the hive. Darker comb that has been used for brood rearing is especially attractive to wax moth larva – be sure to spray those well.

Can I mix a larger batch of B402 Certan solution and use it over multiple days?

It is not advisable to mix a batch of solution larger than what you can use in 24 hours. The solution’s effectiveness lessens over time.

What should I do if I discover significant wax moth damage in my comb?

For frames with significant wax moth damage – it is best to start over with new foundation. While a strong colony can repair small areas, it is not worth their time to make major repairs.

A Final Word

It is wonderful to have this natural solution available as a way to prevent wax moth larval damage in our stored honey supers. Using B402 Certan is a simple process that anyone can do. Don’t let your stored comb be destroyed by moth eggs that may be there – even if you don’t see them.

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  1. What are some of the ways to store frames one intends to use in the next season?

  2. George Cowan says:

    Charlotte – your statement about the coverage for the B402 says “The manufacturer (Vita-Health) maintains that a 5 oz bottle of B402 Certan will treat approximately frames of comb” — However there is no “Number’ between approximately and frames. Just an editing error I am sure but would be nice to know what that number is.

  3. Charlotte Anderson says:

    Thank you – that was a typo on my part.

  4. Hi Charlotte . I just love reading our news. That BT article is a saver! Modern beekeeping with logical thoughts is so much better to understand our little ladies than forty years ago and what was taught in courses by Dr.Ambrose and the older beebooks.

    Thank you so much for sharing your experience which will apply in most cases

    ps I sent you once a picture of a harlequin bee among honeybees on one of my native garden origin Rudbeckia laciniata. It never arrived as far as I can tell. If interested I can find it again and resend. Take care and keep up the good work.

  5. Charlotte Anderson says:

    Thank you. I don’t think I got a pic but I always love seeing pics of bees.