Care sheet guide by DartFrogsAndGeckos.com

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, or more than one, 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. Using the original flies that were used to start the culture will give poor results, the culture should have begun producing new flies at around 10 days from its original start date, and these are the flies you want to use!

Now, your first step to preparing a new culture will be to get all your ingredients/products together. You’ll need media, cups, lids and excelsior. A 1/3rd and 1/2 cup measure will also be needed. You will also need water. I’d suggest getting a gallon jug of spring water from the grocery store, and while you are there, get a quart of distilled white vinegar. When you get home, pour out a quarter of the jug of water, and fill it back up with the white vinegar. Now you are ready to make some new cultures! If you prefer, you can use tap water, dechlorinated, and just add the vinegar as you go. Vinegar is not mandatory but it does produce better results, it is well worth it.

So, we’ll start with a clean deli cup, I generally use the 24oz for the melanogaster flies, but 32oz are fine as well. Using the 1/3rd cup measure, add the media to the cup. Now add a 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. I find that if I pour my water from about 10 or 12 inches above the cup, right into the middle of the media, it will evenly distribute without swirling but either way, you want it to saturate the media. There is no need to boil the water, nor is there any need to add activated yeast to the top of the media water solution.

Now stop and make as many excelsior balls as you will be making cultures. I shoot for a loose conglomeration of excelsior, one that will hold together without dropping pieces of the wood shavings. Put one excelsior ball in each cup. 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 overcrowd 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.

Now we need to harvest the flies we will be using to make the new cultures with. If not done properly, this will make a mess, with flies going everywhere! So, start by getting a clean cup, one of your other deli cups, and put some of your powdered supplement in the bottom. This powder will render the flies unable to walk up the sides of the cup, so it is important. It is worth mentioning that you might want to do this outside, in the garage, or even just using a larger tub, the first few times you do it, since there is the potential to have a bunch of flightless fruit flies running around in your house if you are not careful.

Now, take the culture you plan to harvest the flies from, and knock the flies down in the culture by rapping the culture on the table or other surface where you are working. Do this firmly a couple of times, to dislodge all the flies that were walking around up by the top of the culture. 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 done this a couple of times, 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!

Pro tip: once you are getting more comfortable handling the flies, you can use a more advanced technique for getting the flies out of the cultures…which is to tap them down just like before, then, holding the culture in your right hand, with the base of the cup in your palm, and your fingers on the sides of the cup, use your left hand to crack the lid open, right over the cup you are dumping the flies into…then rap the culture on the lid of the empty cup a couple of times and let the lid close.

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. This is critical!!! 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, typically in the winter. Start small, adding a few drops, and waiting a few hours to see what the effect is. 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. Other options include covering some of the ventilation holes on the lid.

Wet cultures may become soupy around the time the culture begins producing. Adjust the water you are adding accordingly.

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. Unlike with the melanogaster, this is mandatory. We use excelsior, and fill the area above the media with it.

Some people use a cone of coffee filters, moistened and jammed into the media after it has been mixed with water. We used this method for some time, but overall we prefer the excelsior. Bottom line, these flies require some source of cellulose, apparently, as they are developing.

Hydei will definitely do better if you use the 32oz cups, the sudden boom of flies in the cup can result in the culture crashing, all the flies dying from overcrowding/overheating, and being in the larger cups makes this a little less likely to happen. As a side note, if you are unable to use some of the flies on a given day, you may want to offload some of them, let them go outside, or put them in the freezer, because if you leave a full hatching of hydei flies in a culture without removing any of them, you are fairly likely to have a crash. Just keep it in mind!

One other difference in making hydei cultures is that they tend to become soupy and runny around the end of their production. This is nasty and gross, resulting in the media running out of the culture, into your cup of flies and supplement, spoiling all the flies and potentially your day! So, we’ve come up with a hack that really helps this, you’ll find it in the step by step directions, next.

So, start with the 32oz cup, and take a single 12 by 12 paper towel, and fold it into a square that fits in the bottom of the cup. Wet it with water or your water vinegar mix. Place it in the bottom of the cup, and press it to the bottom. Now add your 1/3 cup of media, and then the half inch of water/vinegar mix. Fill the rest of the cup with the excelsior ball.

Now, add the flies, the more the better, shoot for fifty or so, and put the lid on. Date the culture, this is important so you will know when to expect your cultures to hatch. Hydei cultures take about 20 days to begin producing.

Place your culture or cultures on a shelf, preferably away from melanogaster cultures. Hydei seem to tolerate mites well, but the other side of that coin is that hydei always have mites! Hydei cultures are more tolerant of cool temperatures, and seem to do fine in the low seventies, all the way up through the mid seventies. If you need some feeders, you can harvest the flies used to set up the culture if you like, after about a week. Once the culture begins to produce, you’ll want to make a couple of cultures from it immediately, hydei cultures will generally only produce for less than a week. See our other care sheets for more information on the subject of fruit fly culturing for feeding your dart frogs!