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Culturing Fruit Flies

Culturing Information for Melanogaster Fruit Flies

This is a small fruit fly with a short life cycle. It is available in a variety of flightless forms, some with wings, some without. Each is a specific genetic mutation which when crossed with a different mutation will produce many or all normal fruit flies. This means that if you have fruit flies from two different sources, you need to avoid mixing them together. So, if you are ready to start some new cultures, lets go!

First you will need a fruit fly culture that has just begun to produce. Our cultures here are marked with a date, the date the culture was set up. Make sure that this date is at least ten days old, or you run the risk that you will be using the flies that were used to set the initial culture with. Take a clean deli cup or other container, and put some supplement in the bottom. Now knock the flies down in the established culture by rapping the culture on the table or other surface where you are working.

Now take the lid off this culture, and turn the culture over the cup with the supplement. Rap on the bottom of the culture, knocking the flies into the cup with the supplement. When you have enough flies, turn the culture back right side up, and put the lid back on. While you have the culture upside down, you may want to squeeze the culture somewhat, in the middle of the cup, so that the materials at the bottom are less likely to fall out!

When the flies land in the supplement, they will be unable to climb out of the cup, and you will have them confined and easy to work with for a few minutes.

Now take a clean 32 oz deli cup, and measure out a third cup of the media, which is placed in the bottom of the cup. Now add a scant half-cup of water to it. De-chlorinating your water will probably make a difference in increasing production, especially if your water supply is heavily chlorinated. Immediately swirl the water and media to mix the two together. Now add about two dozen flies, more if you have them. Some people like to add a pinch of activated yeast to the culture at this point, however we don't find it to be needed. Now add a handful of the excelsior wood shavings to the cup, so the excelsior touches the media. The excelsior provides places for the larvae to climb out, and pupate. It also provides walking space for the flies, and makes it less likely that the flies will over crowd the culture. On the down side, the excelsior seems to keep the culture more wet, and makes it harder to get the flies out of the culture. It is by no means mandatory, we cultured flies for years without it.

Place the newly established culture somewhere with a moderate temperature. The cultures must get up to around 72-74 degrees for a few hours every day. The warmer, up to about 80 degrees, the better. Warmer temps will result in faster production, and generally result in better cultures. Cultures kept in the very low seventies constantly may be slow to produce and may in some cases not produce. Temperatures much above 80 degrees should be avoided, in particular for prolonged periods.

You should begin to see development soon, the larvae of the flies will begin to climb up the sides of the cup within about five days. After around eight or ten days you will see small brown cocoons on the sides of the cup, and a couple of days after that the next generation of flies will start to hatch. If your culture doesn’t have new flies in it by 16 days, you may have a problem, go back over your procedures, or call us to trouble shoot.

Once the culture begins to produce, don't forget to use some of these flies to start your new cultures with. You will probably need to set up about one culture for every three dart frogs, and you should have some extra. Set up new cultures regularly, until you have too many going, then allow the number of new cultures to settle to a number, which will sustain your collection of dart frogs. Due to the two-week cycle of the flies you should probably set up the cultures every two weeks. As the cultures mature, and then expire, you can wash them out thoroughly and reuse them or throw them away. Also during the last half of the cultures life it may be necessary to add some more water to it, to avoid it drying out. The lids we provide, with the fabric over the holes, are reusable, and should be frozen between uses, to discourage problems with mites.

While the recipe above, of one third cup media to one half cup water, is a good basic recipe, you may find that as seasons change, and the humidity changes, your cultures may change the way they behave. Typically the winter seasons will be dryer, and this can cause the cultures to be a little dryer, and in the summer the opposite may occur and the cultures may be too wet. Dry cultures will form a crust on the surface of the media after only a few days. Small amounts of water can be added to the culture when you notice the crust.
Wet cultures may become soupy around the time the culture begins producing. Adjust the water you are adding accordingly.

Culturing Hydei Fruit Flies

Culturing flightless Drosophila hydei is very similar to the procedure for melanogasters. The main difference is that you will need to use some material in the culture for the flies to climb on, and the larvae to crawl out onto. Some use the same excelsior that we mention above, however we have found the best results are obtained when using the coffee filters we provide in our culturing kits. So, take about twenty coffee filters, and get them wet. Squeeze out any excess water, and shape them into a cone, and press the point into the media. Spread the top of the coffee filter assembly into an open cone. Add the flies, the more the better, and put the lid on. Hydei cultures typically take about 20 days to produce. Hydei cultures are more tolerant of cool temperatures, and seem to do fine in the low seventies. You can harvest the flies used to set up the culture if you like, after about a week. Be very careful when emptying the culture, when it begins to produce. The coffee filter “wad” is going to be heavy, and can fall out of the culture into your cup……yuck! Make sure to pinch the sides of the culture to prevent this from happening!