The wax moth is a highly destructive hive pest that beekeepers should watch out for. In weak colonies, larvae tunnel through comb filled with brood, pollen, and honey with ease, destroying everything in their wake.
The greater wax moth (Galleria mellonella) and lesser wax moth (Achroia grisella) can both damage hives. This guide shows beekeepers how to identify the symptoms of wax moths. Remember that large infestations are easy to spot, but detection isn’t so easy in lower numbers.
What Are The Signs Of Wax Moths?
In the early stages of wax moth invasion, beekeepers may notice cocoons, larval tunneling, bald brood, and cylindrical feces left at the hive’s base. Wax moth eggs are tiny, making them hard to find during inspections. A heavily infested hive will have moth larvae, adult moths, and visible bee decline.
1. Adult moths
The adult moth often lives in parts of the hive that bees can’t access. Keep an eye on the inner cover and top bars, as these are popular locations for them.
The lesser wax moth is ½” (13mm) long and is dull grey with mottled wings and a bronze-colored hind section. Greater wax moths are light brown or grey and typically measure ¾” (20mm) in length.
Their eggs are tiny, so it’s challenging to discover them during a hive inspection. Depending on age, they may be pearly white, light pink, or yellow.
Newly hatched wax moth larvae are creamy white and turn grey as they mature. They grow to over an inch in length and, in the right conditions, become highly active burrowing tunnels through comb.
Beekeepers may confuse the larvae of wax moths and small hive beetle. They both look similar in color and have six legs near their hear. However, wax moth larvae have small prolegs along their bodies. They also lack the two rows of spines that SHB larvae have protruding from their backs. Learn more about the signs of small hive beetle here.
Lesser wax moth larvae are usually solitary, while the greater species gather in large groups.
Quick tip: if you notice one or two larvae between the top bar of a frame and the hive mat, they can be removed and won’t usually result in severe hive damage.
3. Bee decline
A reduced bee population results from serious wax moth infestations. As the bee brood becomes inundated with tunneling and webbing, the colony gets weighed down by these parasitic pests.
Moths can take over a hive in as little as a week if conditions are right. Without beekeeper intervention, a weak hive will eventually abscond.
4. Cocoons stuck to frames
As larvae reach maturity, they form cocoons within the hive. These allow pupae to develop and are generally attached to hive frames. Learn more about the wax moth lifecycle here.
5. Larval tunneling
In the early stages of a wax moth invasion, sighting larvae or adult moths is unlikely. That’s because larvae develop beneath the colony’s brood cappings.
A common way to identify wax moths is by looking for signs of tunneling. As larvae tunnel through comb, they leave white webbing. This silky web can easily be seen spread across the frames and should be dealt with swiftly.
Webbing prevents developing bees from emerging from their cells and results in bee larval death. Honeycomb covered in webs and other waste from these pests can result in unusable comb.
Quick fact: Galleriasis occurs when the webs entangle and eventually starve developing bees.
6. Bald brood
Bald brood results from wax moth larva burrowing through comb. This movement often takes place just below cappings. Cell caps are partially removed as they progress through the hive, causing adult bees to chew the rest off.
The honey bee pupae inside the cell get exposed prematurely, often causing deformities as they grow into adult bees. Moth excreta affects the pupa, resulting in wing and leg deformations.
Bald brood often occurs in a straight line. Beekeepers may notice the next few cells in the line are much lighter or darker than regular capping.
Fecal matter in the hive is a common sign of wax moths and is easy to spot. Beekeepers should check the bottom of the hive for dark, cylindrical feces.
Commonly asked questions
When should I look out for wax moths?
Wax moths inflict the most damage when they are active in warm weather. Moth larvae become inactive in freezing conditions. Metabolic heat allows these pests to continue breeding in the shoulder seasons, so they can still infest hives in early spring and late fall.
What type of comb do wax moth larvae prefer?
Wax moth larvae are highly attracted to pollen-containing dark brood comb. Of course, any comb is at risk, including those recently extracted.
Do wax moths only target hives?
While wax moths enjoy making a hive their home, they will also target comb and pollen in storage waiting to be processed. Wax moths can also live in slum gum and dirty beeswax.
What do wax moth larvae eat?
Wax moth larvae get the most nutrition from dark comb used to store honey, pollen, or brood. Their diet may also include bee larvae cocoons, beeswax, and bee feces.
Can honey bees remove wax moths without the help of beekeepers?
A thriving, well-managed hive will usually remove an invasion of wax moth. Hives with low numbers will initially have unattended combs targeted. As the colony weakens, the pest will become more brazen, damaging combs containing bees.
Wax moth damage will reach severe levels if conditions favor these pests. Beekeepers that discover the occasional single wax moth larva in the hive shouldn’t be overly concerned. Remove it and continue managing the colony to help them become defensive powerhouses.
Small or large healthy colonies usually keep wax moths out of the hive. If you notice more troubling signs of wax moths like larval tunneling, silk, and bald brood, then cocoons and damaged comb should be removed.
Beekeepers can help their hives by properly winterizing them. For small colonies, keep space in the hive to a minimum. There’s less area for bees to defend at a time when they’re more focused on huddling to stay warm.
Finally, unused comb is a target for wax moths. Be sure to take precautions like storing the frames with fumigants or in a freezer.
If you enjoyed this article, we recommend reading our article on the biggest threats to honey bees.