Wax Moths

Dealing with wax moths can be a serious challenge for beekeepers. Both the Greater Wax Moth and the Lesser Wax Moth are often blamed for colony deaths. However, this pest is often a symptom of a larger problem facing the colony. Lets explore why they can be a big issue for beekeepers and share some useful tips to help with control and possible wax moth treatments.

Due to the damage they can do to honeycomb, pollen and honey, even a minimal infestation of wax moths can represent some stress on the hive. Even so, this pest of honey bees has a role to play in the environment and helps keep bee disease from spreading in the wild.

Understanding Wax Moths

Wax Moths (also called “bee moths) are a natural part of the environment. They are attracted to beehives by the scent. Beeswax, honey, bee bread and other hive odors lure the moths inside.

While a wax moth infestation can destroy a colony, most hives will not fail. A colony with a strong population is well equipped to throw those pesky moths out!

However, weaker honey bee colonies are at the greatest risk of severe wax moth damage. For a very small hive already struggling to survive, an infestation of moths may be the last straw.

What Is A Wax Moth?

There are actually two types of these pests that may cause problems in your apiary or bee yard. The Lesser Wax Moth (Achroia grisella) – (left) and the Greater Wax Moth (Galleria mellonella) – (right) are both smaller grey-beige moths. They are most active after dark and often enter the beehive at night attracted by hive odors.

Inside the hive, most beekeepers won’t recognize which type of moth is present. In fact, you may not see one at all – but that doesn’t mean it has not been there.

A strong bee colony with plenty of worker bees is in little danger. Chasing adult moths from the hive and possibly removing moth eggs, bees keep the damage to a minimum.

But, bees generally do not remove wax moth larvae. If there are not enough bees to patrol all the comb, the moth population may get the upper hand.

Why Wax Moths are a Problem

So why are a few wax moths a problem for beekeepers? It has to do with their reproductive cycle. Adult moths want to enter a beehive to reproduce. Their goal is to lay eggs inside the hive that will begin their life cycle.

Life Cycle of the Wax Moth

Female moths can lay up to 600 eggs in clusters on the honeycomb or in crevices of the hive. The spaces between boxes are also a favorite location.

Moth eggs can hatch in 3 days during warm conditions. These larvae (called wax worms by some beekeepers) are the true pests. They are responsible for all of the damage that occurs in the hive.

Wax moth larvae are very small, white grubs. To the untrained eye, they don’t look much different than bee larvae.

In fact, it is not uncommon for a beginning beekeeper to say – “hey, my baby bees are crawling out of the cells!” Hmm – not that is probably not quite right!

In warm weather, the larval stage of moths can be completed in 19 days from hatch. As the feeding stage ends, moth larvae spin white cocoons for the transformation into adults.

They will often eat away wooden surfaces in the hive creating a wavy surface and causing damage to the wooden parts of the beehive. The cocoon stage lasts about 14 days before adult moths emerge and begin the life cycle again.

Diagram of Wax Moth Development

Older, darker black comb that has been used to raise baby bees and hold pollen is very attractive to the adult moths.

This is the type of honeycomb that provides the most nutritious food for their growing larvae. Moth eggs laid in this region will be nearest to their food source.

Contrary to common information, wax moth larvae can live on pure beeswax. This is another reason to try to keep honey bee brood out of your supers intended for honey collection.

This can be accomplished by using a queen excluder and rotating in some new foundation every couple of years.

Webbing & Tunnels

The easiest method of detecting wax moth problems in a hive is the presence of webbing and tunnels in the honeycomb. Moth larvae leave behind noticeable tunnels with a “spider-like” webbing.

In unguarded comb, they continue to eat until all the wax has been consumed. Leaving a webby, mess for the beekeeper to clean.

Sometimes, wax moth larvae can be found crawling on the comb surface or the bottom board. The larvae are easily confused with Small Hive Beetle larvae, another bee pest.

Frass

Frass is the excrement of insects. Larval feces (small cylindrical black pieces) can also be seen on the bottom board and in the webbing on the comb.

Bald Brood

As wax moth larvae tunnel through the comb just below the cappings – they may cause a condition called “bald brood”. The moth larvae are partially removing the cell caps as they burrow.

Then, worker bees use their tooth-like mandibles to chew the rest of the cap off. This exposes the head of developing bee pupae often resulting in deformed adult bees.

Wax Moth Treatment and Prevention

The best way to treat wax moths in your hives is to avoid letting the situation get out of control. There is no safe chemical that you can put in your hive to kill moth larvae and not damage the bees.

Here are some techniques that can help your bees be able to defend themselves against wax moths.

• keep colony populations strong
• do not put too many boxes on the hive
• monitor hive population all season
• outside moth traps

Strong Colony Population

Keep strong healthy colonies with lots of bees. Are there enough bees to cover most of the comb surface? Wax Moths can be a problem during any of the warm months of the year.

Be careful with new colonies or when making splits – you need enough bees to patrol the comb. When you split a bee hive, failure to include enough bees in each part could lead to problems with moth damage.

Any time you mix warm weather conditions with weak hives, there is a potential for a wax moth infestation.

Likewise, a colony that loses it’s queen may dwindle in population unless the beekeeper is able to requeen the hive in time. Monthly inspections are a minimum during warm weather.

Avoid Too Much Space

Avoid adding supers to the hive if the population can not patrol the comb. We all make this mistake sometimes as we prepare for the honey flow.

A new hive started from buying bees in a package will need several months to build a population. It may be a target especially if the beekeeper adds too many boxes at once.

Monitor Hive Population Changes

Monitor the population of your hives during the season. If a colony swarms and experiences a dramatic drop in bee population – they could be at risk.

Also, the loss of a queen or other issues related to brood production could result in a reduction of bees available to protect the comb surfaces.

Wax Moth Trap & Recipe

It is near impossible to keep wax moths out of a hive. In my opinion, it is an exercise in futility to try. However, some beekeepers do set up various types of moth traps near the bee yard – maybe they help?

This is a common one:

• Use an empty soft drink bottle – with a one inch hole placed near the slope of the neck.
• Fill the bottle with 1 cup of water – 1 cup of sugar, ½ cup of vinegar – add a banana peel. Let this mixture ferment for a couple of days.
• Then, tie it to a tree near the bee yard.

Experiment with different bait recipes. But don’t expect traps to be the complete answer to moth problems. They will not make up for good hive management.

Strong Colonies Can Repair Wax Moth Damage

Seeing an adult moth or a few moth larvae is no cause for panic. Even a strong colony may have the occasional moth or wax worm.

In the case of a minor problem, the bees will clean and repair damaged comb. Remove the frames that are most infested or damaged and reduce the hive size down to fewer boxes.

A 2 deep hive may need to temporarily be reduced to a 1 story deep. A single deep may need to be in a 5 frame nuc for a while-until the colony population rebounds.

Protecting Stored Honey Supers

One of the biggest mistakes made by new beekeepers is improper storage of honey supers. Your bees did a great job and you want to save all that beautiful wax for them to refill next year.

Well, Wax moths are not only a danger to occupied hives. In fact, they do some serious damage to drawn out comb. 

Moth eggs can be present on those frames even if you don’t see any. Then, you place them in a nice dark place – perfect for moth larva – they love the dark.

If you must put your supers away, be sure to prepare them first. Freeze comb (frames and all) for a few days and then place it in a tight storage container.

Or use approved chemical repellants designed for this use. Another option is the use of a Bacillus Thuringiensis (Bt) solution such as Certan B402.

Cleaning Up a Hive

If you have been in beekeeping for a while, you have likely experienced a box full of moth larvae and webbing. What a mess.

Comb that has a moderate amount of damage can be reworked by a strong colony. You may find a few bees trying to hang on or the colony may already be dead. If your bees are all gone (or too few to survive), it is best to disassemble the hive.

• remove the mess (webbing, cocoons etc.)
• replace foundation if needed
• freeze any decent combs from the box
• scorch interior of hive box (optional)

Scrape away any comb debris webbing etc with your hive tool or a scraper. You will need to scrape pretty hard to remove cocoons containing wax moth pupae.

Beekeepers who use plastic foundation have less of a clean up job on wax moth infected frames. They can scrap the mess off that plastic and the bees can reuse the foundation. You could pressure wash the foundation but there is usually no need.

Those of us who prefer beeswax foundation need to keep extras on hand so we can install new wax foundation when needed.

Any “good” frames of comb that you remove from the hive should be frozen for 2 or 3 days to kill any moth eggs and then stored in a moth free place until needed.

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