How to get rid of fruit flies

I love fruit flies. I even study fruit flies for a living. Whenever I tell someone this, most people have fruit fly-related experiences they would like to share: “I have a lot of them in my kitchen. You can get some if you like. How can I get rid of them?” So, here is the answer to that question. 

But first, you probably also have another question in your mind: “Why do you study fruit flies?” The answer is that I don’t really study the fruit fly because I want to learn more about flies. I use the fly as a tool to try to understand what is going on inside us humans. 

Believe it or not, but we have a lot in common with the flies. We both have organs like heart, intestine, ovaries and brain. Both humans and flies are made up of cells that work in the same way, and in fact the majority of our genes you can also find in the fly. However, it is both easier, cheaper and more ethical to experiment on flies than on humans. 
The fruit fly has no less than six Nobel prizes, and has been used in research for more than a century. We use the fly to study aging, obesity and alcohol abuse. We send fruit flies up in space and we use them to develop vaccines. We use them to understand a great variety of diseases ranging from Parkinson to cancer.
I use the flies to investigate how one cell can divide and become two cells. I want to understand this because cancer is cells that divide uncontrollably. Knowledge about cell division is therefore important to understand and treat cancer.

So, let’s go back to the question of how I kill my fruit flies. Here is how I do it:

1. Kill them by hand
Most of my experiments rely on very advanced microscopes, and I use it to look at dividing cells in the fly ovary. To do so I must first get the ovaries out of the flies. To do this, I use a pair of very sharp tweezers. I crush the head with one tweezer and rip the flies open with the other. Then I can take out the ovaries, and the fly is dead. Mission accomplished. 
I realise that this approach might not be very useful to kill flies living in the fruit bowl on your kitchen counter. 
No worries, I have another suggestion. 

2. Kill them with a sip of wine
In the lab, I often want to combine specific genes in one fly. Maybe I want to combine the modified gene A with a destroyed gene B. Then I need to select potential mummy-flies with gene A, put her together with daddy-flies with gene B and hope for some love. 
It is very hard to pick the future parents when they fly freely around in the lab. I need to make them lie still. I solve this problem by gassing them with CO2 until they pass out, and I can collect the ones I want. The ones I don’t need get poured into a big vial of alcohol, drowns there and never wakes up from their nap. They die. 
I realise that you might find it annoying to waste perfectly good alcohol on some irritating fruit flies. Therefore here is another option: 

3. Kill them with large gas tanks
A third way I kill fruit flies at work is to put them in closed vials, throw them in the trash. Later the trash is incinerated. To get the flies in the vials I use more of the CO2-gas, but having big tanks of compressed CO2 at home is dangerous. Gassing down your kitchen with CO2 might put you to sleep as well.
So, let’s see if I can come up with a safer and healthier way to get rid of the annoying creatures zooming around your kitchen. 

4. Kill them with no food 
So far, none of the ways I kill my fruit flies at work are suitable to get rid of unwanted, flying guests in your kitchen. But I think the last approach would work. This expert tip is not something that I would not tell my boss about, and it is not something I do intentionally.
My fruit flies need to be fed regularly. Sometimes, a vial full of flies gets unintentionally lost in the back of the incubator; flies that I have completely forgotten about, flies that have not gotten any food in weeks. And they are dead. Very dead. 

So here is the solution to your fruit fly problem: Take away their food. Remove fruits and other types of food from the kitchen counter, bring the trash out often, and hope that the banished flies find a new home somewhere else. But when doing so, send a few loving thoughts to the flies. After all, they have contributed to science for more than a 100 years.

By Anette Lie-Jensen
Published June 12, 2018 2:51 PM - Last modified June 12, 2018 3:15 PM

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