Flies without tears – a personal approach to maggots

Livefood is an important dietary component for successful breeding of many of our finches. Despite the better balanced and more nutritious diets now available for birds – including some excellent softfoods, half-ripe milkseed and various supplements – it seems that nothing quite replaces the need for livefood of some type.

Finch breeders utilise three main types of livefood – termites, mealworms and fly maggots, sometimes euphemistically called “gentles”. Of these, termites are probably the best if you have the time to maintain a reliable supply, while mealworms appear to be nutritionally unbalanced if fed as the sole livefood. For an increasing number of finch breeder, maggots are now the standard due in large part to the ease with which large quantities of high quality livefood can be generated and the relative simplicity of the breeding system for flies.

What follows here is very much my personal method for producing this valuable livefood, but there are many variations that can be tried and just about anyone you speak will have slight personal preferences on how they approach it.

The fly normally used for maggot production is the bushfly – Musca vetussimma- which is a little smaller than the housefly and adapts well to intensive culturing in cages and importantly can utilise simple protein-based diets without meat. The fly lifecycle is similar to many other insects which go through a pupal stage [so-called holometabolous insects] with four basic stages – eggs, larvae [the maggot], pupae and the adult fly.

Much of the early work in perfecting fly rearing was done by Craig Smeelie in Victoria and his basic techniques have now been adopted widely.

Basic Requirements

1. A Secure Fly Cage.
Having obtained some fly pupae from a friend the first requirement is a secure cage. A simple box of 40 cm x 40cm x 40 cm with gauze on the front and a light bulb mounted on the inside back wall is what I use. The cage walls should be painted or sealed so as to be easily cleaned. I have also seen fly colonies in cages made entirely from mosquito netting on a light wire frame. Whatever you use it is critical that the flies can’t escape. Because you will need to be in and out of the cage regularly, a fly proof door is essential. I use an old stocking secured around the edges of the door opening and simply tied in a knot. The stocking will gather holes over time, but is easily replaced. Keeping your flies in will help with neighbourly relations. As shown in one of the photos I leg ring all my flies, so that I can be sure which ones are mine!

2. Temperature Control.
It is important that you can maintain the temperature environment for the flies. They need a stable temperature if possible – 26o to 27o is ideal, so they will need to be kept warm during the winter and protected from excessive high temperature during the summer. A 60W light bulb in the cage provides effective warmth in winter and a cloth cover can be draped over the front of the cage to hold in the heat. During summer a lower wattage light [25W] might be better. Eggs and hatchling larvae also need to be kept warm to ensure rapid development but once they are growing the maggots generate a lot of metabolic heat and it is important to ensure they don’t get too hot – otherwise you can easily end up with cooked maggots – not a pleasant outcome.

3. Food and Water for the Flies.
The adult flies need a simple diet of sugar and water. I provide water in a small plastic food container with a 1.0 cm hole bored in the lid. The container is filled with water and then through the hole I insert about half of a 15cm long cotton dental wick. The other half of the
length is laid flat on the lid. Water is drawn up through the wick and the flies simply suck it out. This simple method avoids open containers in which the flies usually drown or the need for regular spraying of water into the cages, and ensures the flies have
water all the time. While some say that water is not necessary I believe fly longevity is much greater with water provided. The water container is cleaned and refilled weekly and to keep the water clean and fresh I add a “dash” of Aviclens each time. Sugar is necessary to provide the energy needed for flight. The flies don’t require any protein – all the protein needed for a female to lay her lifetime of eggs is accumulated during the larval stage and carried through into the fly. I provide sugar cubes in a small dish at all times. It is amazing how much sugar several hundred flies will consume.

4. Rearing food for the maggots.
This is where there is great variation among maggot aficionados, but the basic medium for collecting eggs and then rearing maggots is pollard mixed with milk powder as a protein source. Some people use bran or “mill run” which are more easily sieved out later, but I find pollard is fine.

I use two different mixes for the maggots. The first mix is used to collect eggs and feed the hatchling maggots. The second mix is used to feed the maggots as they develop. The first mix consists of four parts pollard with 1 part full cream milk powder and then add about 2 parts of water to produce a moist crumbly mix. Adjust the amount of water a little if needed but the final mix should be moist, not sloppy wet! Some breeders also add meatmeal and other additives to their mix, but provided the maggots have a readily digestible source of protein [like milk powder] and they grow rapidly their eventual nutritional quality will be much the same. I place the bran and milk mix in plastic butter containers (filled to the top) and then place these in the fly cage. The flies will quickly swarm all over it and commence laying eggs directly into and onto the mix. Leave the mix for 2 days then remove and replace with containers of fresh pollard and milk mix.

The second mix is used to feed the maggots again about 1 day after hatching. It is important to feed your maggots sufficiently. Often if I have huge number of small maggots I divide them into 2 or 3 large containers and then feed each group one more and sometimes twice more over 2 days. This second mix is 3 parts pollard, 1 part medicated chick start crumbles, 1 part powdered milk, plus 2 parts water. This mix contains more protein and will ensure the maggots have plenty of nutrition to complete development.

Getting into the Routine

Having got this far it is now important that you get into a set routine of replacing the egg collecting mix, allowing the eggs to hatch and then monitoring maggot development to a stage where they are ready to feed to your birds. At 26o, fly eggs will hatch in about 36 hours, maggots then take 3-4days to develop and then pupate. They remain as pupae for about 5 days then emerge as flies and live for up to 10 days. They will commence mating and egglaying about 2 days after emergence.

So to ensure a continuous supply of maggots it is important to follow a routine, but before I comment on that a couple of other points:

1. It is much better to have large numbers of flies in your cages, than just a few. This will ensure that lots of eggs are laid, lots of larvae hatch in each container of food and that they develop rapidly. The larvae generate a considerable amount of heat – metabolic heat – when developing and the faster they develop the more effectively they will consume all the food and turn it into a dry brown powder. With only a few larvae in the diet, they will develop poorly, the mix will ferment and you end up with a smelly, wet mess.

2. to maintain large numbers of flies it is critical that at least once a week one batch of maggots is allowed to complete development and pupate and then be placed back into the cage. This will ensure fresh flies are emerging regularly.

My routine is as follows:

I have two fly cages, each with at least 1000 flies. In each cage I place two containers of egg collecting mix every two days. The 2 previous containers, now loaded with eggs are removed and placed in a warm, dry place for 24 hours until the maggots have hatched and partially developed. I then tip them out into a larger plastic cake container, stir the mix around a bit and leave again for 24 hours after which they should be ready to feed.
Sometimes when there are huge numbers of maggots they will rapidly consume all the food and still be quite small. At these times it may be necessary to add a little more bran and milk mix for the final 24 hours of development. Once a week I put one container of maggots aside, provide them with extra food to ensure they develop into big fat maggots and allow them to pupate. These produce large productive flies. One container will produce many hundreds or thousands of pupae. These are mixed with some dry bran and placed back into the cage to emerge as flies. It should be clear that essentially there is something to be done every day. Since I keep my flies in the garage I can do all the colony maintenance at night.

Feeding your birds.

When still feeding the maggots will have a dark line of food clearly visible in their gut. Don’t feed them at this stage. Maggots which are ready to feed to the birds should be pure milky
white as in the photo. When they have completed development and are ready to pupate the maggots will empty any remaining gut contents and that is when they are ready to feed out. I usually wait until some have pupated before feeding them out since this means most of the maggots will be ready [see picture].

Maggots can be stored in the refrigerator for several days and this can be useful because the maggots will all aggregate together into a ball. Before feeding I can then easily remove much of the used medium. In this way I avoid having to sieve the maggots and pupae from the used food. Once I have just maggots with a little of the used food I mix in a couple of handfuls of fresh, dry bran. The final product fed to the birds is then a clean and dry mix.

The 3 C’s of fly breeding

There are three critical things to apply for effective maggot production:

Cleanliness – it is important that all the maggot rearing containers are thoroughly cleaned after each use, that the water is clean, that the fly cages are cleaned occasionally and most importantly that the maggots are fed after they have evacuated their gut contents in a clean dry mix.

Consistency – routine is everything. Don’t change your egg collecting mix in an irregular way and don’t forget to place pupae back into your fly cage – otherwise your population of flies will decline and you will end up with peaks and troughs of production and inevitably have a couple of days with few maggots. These might be crucial days for your best pairs of birds and their young.

Control – it is important to control the environment for your flies. Like all insects all their development is temperature dependent, but they have preferred temperatures. Don’t let them get too hot – the flies and the maggots will die. Don’t let them get too cold – everything will slow down and maggots won’t develop well. So it’s that simple! Once you are into a routine it really is very simple to produce ample quantities of hygienic and high quality livefood this way. I find that all my finches take maggots readily and breeding results have been good.

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