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Kombucha Fruit Flies

Kombucha Fruit Flies

We have written about many topics here, but it finally occurred to us that we somehow overlooked one of the most common issues all kombucha brewers will come across – the kombucha fruit fly. Fruit flies, also known as gnats, barflies, vinegar flies, drain flies or pomace flies, love kombucha. When it comes to kombucha enthusiasts, fruit flies are right there at the top. Fruit flies are incredibly resilient, and once you have them, getting rid of them can be challenging. Having fruit flies in, on, around, and just merely flying in the vicinity of your kombucha can be frustrating. 

What do you do when you have a fruit fly problem?

To get rid of fruit flies, you need to find and remove all possible food sources and locations that the female fruit flies are laying their eggs. You will also need to eliminate the adult population so they can’t breed. The lifespan of a fruit fly is between 30 and 50 days, which is heavily influenced by the temperature. While this may seem like a short period, females are capable of breeding and laying several batches of eggs during their lives. Each time a female breeds, she can lay up to 500 eggs, quickly multiplying the population. This rapid breeding is what makes it so difficult to control the population once established. 

 Life cycle of the fruit fly

  1. The female lays her eggs on decaying organic material like a piece of fermenting fruit. 
  2. The eggs hatch into larvae and begin eating the organic material in their nesting site. 
  3. Larvae then find a dry, dark place for pupation, which takes about four days.
  4. The larvae emerge as adults and can begin mating as soon as two days later. 

How to get rid of kombucha fruit flies?

To successfully get rid of fruit flies, you need to stop them from breeding and prevent their eggs/larvae from becoming adults. To stop larvae from becoming adults, we must first find the food source where they are laying eggs.

How to find where fruit flies are laying eggs?

Fruit flies can lay their eggs on basically any decaying organic material. If you are having trouble finding the source, use this list to help find typical fruit fly hangouts. 

  1. Fruit flies love freestanding water. Find and eliminate any source which can include leaking pipes, old mop buckets, or the sink. Remember, they are also called drain flies. So if your sink is the problem, try mixing a capful of bleach with 12 oz. hot water, pour it down the drain, and cover with a stopper. 
  2. Fruit flies love rotting food. Make sure all trash bags are tied, and all trash cans covered. 
  3. Fruit flies also love dirty dishes, maybe now is the time to tackle that old pile in the sink. 
  4.  House plants can also be problematic, especially since they often aren’t seen as an issue. Low-quality potting soil can contain decaying organic material and fungi, which attracts fruit flies. If you notice fruit flies around your houseplants, you may want to switch to a higher quality soil.

Now that we eliminated the nesting sites, let’s get rid of the adult population. 

How to control the adult fruit fly population?

The most popular way of killing fruit flies is with a trap. Whoever said, “you catch more flies with honey than with vinegar,” clearly never met the fruit fly. When it comes to catching fruit flies, vinegar traps are your best friend. However, fruit fly traps can be baited with just about any decaying organic material, including kombucha. The most commonly used baits, however, are vinegar, wine, or fruit. Apple cider vinegar traps are extremely effective. For large infestations, a vacuum or an electric fly swatter are also great tools – a lot of fun too.     

How to make a kombucha fruit fly trap?

A DIY homemade fruit fly trap can be quickly made. In a small cup or bowl, mix some kombucha with a small amount of dish soap. The kombucha may be substituted with just about any vinegar, fruit juice, wine, cider, or beer, to name a few. Now place the container in or near the area of your fruit fly problem. The flies will be attracted to the kombucha and land in the liquid. Once in the liquid, they will have a hard time getting out and subsequently drown. Some may opt not to include the dish soap, but I recommend it as it helps keep the flies trapped in the liquid. You can take this a step further by covering the vessel with plastic wrap and poking small holes in it. The flies will find their way into the container through the small holes but won’t be able to get out, and you guessed it, kill the fruit flies.  

Electric fly swatter or a vacuumKombucha Electric Fruit Fly Swatter

When you have a severe infestation involving large numbers of fruit flies, electric fly swatters work great. An electric fly swatter is incredibly effective at wiping out large numbers and it’s a lot of fun to use. A vacuum can also be equally effective by sucking them out of the air. The vacuum and electric fly swatters work best when you are in a situation where they gather in large numbers and you can sneak up on them. 

Why are fruit flies attracted to kombucha?

Fruit flies are attracted to acetic acid. Acetic acid is in vinegar and is created during the vinegar fermentation process. Since kombucha is a vinegar ferment, acetic acid is produced during the fermentation process as well. Vinegar fermentation is a two-step process that occurs in succession when making kombucha. First, the yeast consumes the sugar in the sweet tea and produces CO2 and ethanol. The bacteria in your culture will then consume the ethanol created by the yeast and produce acetic acid, and the fruit flies go wild. 

How to keep fruit flies away from kombucha?

Keeping flies out of your kombucha usually isn’t a problem. You just need to keep your kombucha brew covered. Beyond that, make sure the material you are using to cover your kombucha jar has a tight enough weave to prevent fruit flies from getting in. Some styles of cheesecloths aren’t weaved close enough and will let bugs in. These gaps can usually be eliminated by doubling or tripling the cheesecloth over the jar. Coffee filters also work great. Our favorite fabric cover for kombucha has to be muslin. In addition to its tight weave, these unbleached muslin covers check all boxes – breathable, durable, and washable.  

What to do if your kombucha has fruit flies in it?

Finding fruit flies in your kombucha can be upsetting. If you have an infestation, unfortunately, your best bet is to start over as the larvae could be present on the pellicle itself. 

Keeping fruit flies away

Once you have the fruit fly population under control, you’ll want to keep it that way. So you will need to be mindful of possible breeding locations moving forward and not letting them take hold once again. However, if you start seeing fruit flies again, you will want to start the whole process by repeating the steps above. 

Have you gotten rid of fruit flies using another method? Leave a comment below and tell us about it.

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