Wax Moths

John Skillcorn

Important notice
The Greater Wax moth, Galleria mellonella, can become a serious pest of beehives.  Please consider your local bee keepers and do all you can to prevent this insect escaping into the environment.

The Wax Moths are, in my opinion, some of the most useful live-food organisms to have been brought into culture. They are almost the perfect food animals: prolific, thrifty on space and very easy to maintain in a healthy condition.  However, I must immediately say that although larger animals e.g. lizards, large amphibia, take the larvae readily, they are not suitable as food for all species of Dendrobatid frog.  I have had occasions when, after taking several tiny larvae, frogs such as D. auratus have brought the larvae back up.  There is clearly something in the larva's makeup that does not agree with all frogs and I would hazard the guess that it is the skin.  The following notes are provided for the sake of completeness and for those people who like to experiment.

Introduction
Many years ago I began culturing the Lesser Wax Moth Achroia grisella for the purpose of using them as live food for small Cyprian geckos. Our school beehives were infested with them and so it was a simple matter to obtain a starter culture. However, as I did not know of any artificial diet at that time, I had to rear them on natural honeycomb. As I have rarely encountered a more ravenous animal than a Wax Moth larva, our bees were kept very busy providing food supplies for my cultures!

However, the development of a good, artificial diet has meant that vast numbers of these insects can be reared in little space. They have the added advantage that they are available in two different 'textures' - the tough, chitinous adult moth and the soft, nutritious grub. Although they are made of the same basic proteins (being the same species), it must be an added benefit with regard to roughage and bulk, providing that the predator being maintained is of a sufficiently large size to take all the stages.

Artificial diet
The recipe I used was supplied to me by Edwin Blake of Edinburgh. The addition of beeswax is most important, I find, and it makes all the difference to the successful, rapid start of the culture.  It is not, however, absolutely essential.  The recipe is made up in two parts:

Mixture 2
200 g milk powder (Cow and Gate)
200 g wholemeal flour
100 g yeast powder (dried brewer's yeast)
100 g wheatgerm
400 g bran

Mixture 1 should be prepared first and then mixture 2 (each separately), and then mixture 1 should be blended thoroughly into mixture 2. In addition, I mix in liberal helpings of Vionate, Stress and SA 37, as well as topping the whole thing off with grated beeswax. This all makes for a rather wet mixture somewhat like partially melted toffee, and there will be enough to set up several smaller cultures or one (very) large one. 

Culture vessels
I kept my cultures in big, plastic bread bins from Savacentre, the lids of which having had a large section removed and replaced by metal gauze glued in place with silicone adhesive. Nevertheless, the beasts still got out, and people who called for coffee often passed the time by playing 'Spot the Moth'. Apart from frightening little children and the elderly, they did little damage - my cats at least appreciated savouring the quick snacks as they fluttered past! 

General maintenance of cultures
Whatever culture vessel you finally decide upon, bear in mind that these larvae have an amazing ability to chew through almost anything that is not made of either glass or metal. How they actually achieve this on super-smooth nylon beats me, but they do! When first set up, the culture appears to stand still. The original moths, however, will have laid thousands of eggs, and the larvae which hatch from these are extremely tiny, remaining well hidden for a few weeks. Then, suddenly, they seem to appear from nowhere and chomp through the food at an alarming pace. At the same time they generate a tremendous amount of metabolic heat, and the base of the culture will be distinctly warm. Not only that, but water produced from respiration will condense on the inside of the lid and sides of the container, even if it is well ventilated.  This can cause the medium to become rather too wet and soggy.  In order to overcome this problem, it may be prudent to line the containers with several thick layers of newspaper, and my experience indicates that this does tend to keep the food supply a little drier. 

The food supply will run out, and in the case of the Greater Wax moth this can happen literally overnight. You must, therefore, keep a very close eye on this, and be ready to replenish the food when necessary. This is not the same sort of problem with the Lesser Wax moth.  The life cycle of this insect is rather more staggered, and it is normal to have all stages of the insect present within the same culture.  Wax need only be used for brand new cultures, and once the culture is in full swing it is no longer needed.  Having said that, it will undoubtedly be beneficial to add a little every now and again, if you can remember to do so. 

Full-grown larvae are quite sizeable, and will leave the medium in order to pupate. They spin a small, oval cocoon of white silk, which is tough and papery to the touch. From these the moths hatch after a period of a week or two, depending on the temperature. The moths mate almost at once and the female begins laying hundreds of eggs in any nook or cranny available.

The female is a fair bit larger than the male, and is a lot darker. As she lays, she runs rapidly over the surface of the medium, poking her ovipositor into suitable niches. The adults do not feed, but live for a couple of weeks before dying. Cultures can be a bit tricky to open at this time, but cooling them a little makes them slightly easier to handle. The insects are eagerly taken by most geckoes and larger frogs which, because they are so agile, put on fantastic displays as they hunt out the moths and capture them. The larvae, on the other hand, will serve as food for any animal, from tiny Poison Arrow frogs upwards, due to the vast range of sizes in which they occur. 

The whole life cycle takes around six weeks.

Although I started out with the Lesser Wax Moth, most people seek to maintain the Greater Wax Moth Galleria mellonella due to its much larger size (in fact, about twice the size of its smaller cousin).

General notes:
Another useful species is the Mediterranean Flour Moth Ephestia kuhniella. This moth is very much smaller than Galleria, and darker in colour. It is not quite so easy to culture, due to its selfish habit of going into diapause whenever it is maintained with less than 16 hours of light out of every 24. 

It can be cultured using exactly the same medium as for wax moths, although it may also be kept quite successfully using simply a mix of wholemeal flour and dried yeast in the ratio of 9:1, and then mixed to a crumbly texture with glycerol. It is recommended (although not essential) that all materials be heat sterilised at 105°C for 2 - 3 hours. 

The culture vessels should be around 250ml capacity, stoppered with foam or cotton wool, and into these should be placed 40g of medium. Incubate at 25°C for a life cycle of 4 - 6 weeks. As mentioned before, to prevent diapauses, a light regime of 16 hours light and 8 hours dark should be employed throughout. 

These moths seem to appreciate small rolls of corrugated cardboard in which to pupate.