I Spy A Fly

I tested to see what liquid would catch the most fruit flies. No fruit flies will be harmed
Signe Johannesson
Grade 6



If I place four bowls with four different liquids which are apple juice, ginger ale, apple cider vinegar, and red wine then the fruit flies will be more attracted to the apple juice because apple juice has more sugar than all the other liquids and fruit flies love sweet and sugary things 




Fruit flies are smart and small insects. They are super fast when it comes to catching them. Fruit flies can turn quickly and that causes them to fly faster than they usually would, and it helps them to avoid predators. Fruit flies names aren’t just fruit flies Their actual name is Drosophila melanogaster. Fruit flies are attracted to sweets and fruit such as candy, fruit, and sometimes vegetables. Fruit flies main diet is overripe fruit and vegetables. Most of them hang around compost bins or garbage disposals because they are attracted to the rotting fruit. (Potter, n.d.)

Everyone hates it when fruit flies are in your house and roaming around your fruits and vegetables, but there are some ways people get rid of fruit flies. Some people use fly swatters to kill flies, but fruit flies are very tiny and there are so many of them if you use a fly swatter you won't be able to catch them so it's not an efficient way. Some people use apple cider vinegar or red wine to catch the fruit flies by putting the attractants in a bowl and they wrap plastic wrap around the bowl, they poke tiny holes not that big so the fruit flies can get out but the right size so that the fruit flies can go in the bowl. The fruit flies get attracted to the sweetness of the wine or vinegar and go into the bowl. Once the fruit flies go into the bowl then they go into the wine or vinegar and drown.

In this experiment, I will be using four different types of attractants. My attractants are red wine, apple cider vinegar, juice, and soda. Red wine is mostly made out of crushed grapes. Apple cider vinegar is made out of crushed apples and a bunch of vitamins such as B1, B2,and B6. The following chart shows how much sugar there is in each 50 ml of liquid (

Apple juice (50 ml)

Ginger ale (50 ml)

Apple cider  vinegar (50 ml)

Red wine (50 ml)

6 grams of sugar

4.51 grams of sugar

0.2 grams of sugar

0.40 grams of sugar

Based on all the research we went over, fruit flies really like rotten food, fruit, and other sweets; they like fruit because they lay baby larva on the fruit. So if you grab a strawberry or apple make sure you wash it before you eat it. According to Harris (2015), Fruit flies love fruit but there are some things fruit flies don’t like. Some of these things are basil, Peppermint, Eucalyptus, Lavender, Clove, and Lemongrass. They hate the smell of basil because there are three specific chemicals that are found in basil that are lethal to fruit flies. If you put these scents all around your kitchen there will be fewer fruit flies. (Harris, n.p)

Fruit flies are very interesting and gross and they love fruit. They dislike some scents but it won’t stop them from going to the fruit. 

 In case you're wondering what fruit flies look like adult fruit flies have red eyes that are 3 to 4 mm in length. The front of the fruit flies body is beige or brown in color, and the back portion has dark stripes. 







Manipulated variables: type of liquid in each bowl,    

Responding variables: How many fruit flies go in each container 

Controlled variables: Size of container, measurement of liquid in each container 




  1. Get out four containers and put cotton balls in each one then put two pieces of fabric on the cotton balls and pour each liquid (50 ml) into each container and the liquid will soak into the cotton ball and the fabric. Make sure you label every container.
  2. Put plastic wrap around the top of each container and make sure the lid is off. You can put tape around the plastic wrap and connect it to the container if you want to have more protection. 
  3. Poke 16 very tiny holes in the top of each plastic wrap with a toothpick about 1mm in size not too big that the fruit flies can get out of the container though 
  4. You can put containers and the fruit flies in a terrarium so they do not escape  
  5. Now you wait …
  6. Each day count the fruit flies in the containers and record this in a log book. let them free at once you counted them each so they will not be harmed by you in anyway. 
  7. Repeat this for five days
  8. A week later add the count of fruit flies that you got on every day in each container and you will have your results.


  •  Apple juice
  • Apple cider vinegar 
  • Red wine 
  • Ginger ale 
  • Four containers 
  •  Plastic wrap
  •  Tape (optional)
  •  Toothpick
  • Measuring cup
  • Cotton balls
  • Organic cotton fabric 






I Put three stretched out cotton balls at the bottom of the container. Then I put two layers of fabric over top of the cotton balls. Next I poured 50 ml of the liquid I am using into each container. The liquid soaked up into the cotton balls and some of the fabric on the top so you could still smell the liquid. IMPORTANT NOTE; I had to buy the fruit flies because we did not have enough fruit flies to this experiment. These fruit flies are modified to not fly but they will still be able to crawl onto the container. I poked sixteen holes into each plastic wrap and then I put them into the terrarium. I put the fruit flies in the center and let them roam around. We started the project at 4:30 Monday March 8th (2021)

Day 1

Most of the Fruit flies escaped from the terrarium. From what I saw the fruit flies did not seem very attracted to any of the liquids however we moved the fruit flies into a different bin so they won’t escape. Once we move the containers into a different bin we added more fruit flies because the others disappeared. There was four fruit flies in the Red wine, Three in the ginger ale, Three in apple cider vinegar, and one fruit fly in the Apple juice. We observed this for day one at 5:00 tuesday March 9th (2021)

Day 2

All the fruit flies were standing still and not moving. When I went to count the fruit flies they were on the edge of the plastic wrap and none in the container so I counted the fruit flies that were on the side of the plastic wrap. I think maybe the fruit flies can't get in the container so I made each sixteen holes bigger so they can get in effortless.after we counted the fruit flies on the containers we put some more fruit flies in the terrarium so the count will be greater. There was ten fruit flies in the red wine,There was between 17 or 18 fruit flies on the Apple juice, fifthteen in ginger ale, andand 11 in apple cider vinegar. Day two observations started at 4:10 Wednesday March 10th (2021)

Day 3

There was way more fruit flies in the containers than the start of the experiment. I think making the holes larger on the plastic wrap really impact the results of day three because there was more fruit flies that could get into the container. After I counted the fruit flies I let them out of the containers and put them back in the terrarium. The end result was red wine had 24 fruit flies, apple juice had around 23 fruit flies, ginger ale got about 34 fruit flies, and apple cider vinegar had 22 fruit flies. Day 3 observations started at 4:00 Thursday March 11th (2021) 

Day 4

I saw when I was counting the apple juice that there was some mold and bacteria growing in the apple juice container and I think that might affect the result. I also noticed that the red one didn't have as many fruit flies as the other liquids.When I was done counting I put some more fruit flies in the terrarium to see if they would go to the red wine more than the other liquids. There was six fruit flies in red wine, 22 fruit flies in the apple juice, 24 fruit flies in ginger ale, and 21 in the apple cider vinegar. Day four observations started at 6:00 Friday March 12th (2021) 

Day 5

The mold in the apple juice turned black. It looks like tiny black dots everywhere. It also look like on day 5 apple juice have the most fruit flies. Because I made the holes bigger on the plastic wrap there was more fruit flies in the containers. I let all the fruit flies free outside once I was done the experiment. Today's result were that red wine got 28 fruit flies, apple juice had around 49 fruit flies, ginger ale had about 42 fruit flies, and apple cider vinegar had 46 fruit flies. Day 5 observations started at 6:00 Saturday March 13th (2021) 






My results were very interesting. Based on the results, I believe that my hypothesis basically correct. This is because the two liquids with the most sugar attracted more of the fruit flies.The results were,

#1 Ginger ale: 115 fruit flies from each day

#2 Apple juice: 112 fruit flies from each day

#3 Apple cider vinegar: 100 fruit flies from each day

#4    Red wine: 67 fruit flies from each day


Red wine

Apple juice

Ginger ale

Apple cider vinegar

Day 1



Day 2





Day 3





Day 4




Day 5






67 fruit flies

112 fruit flies

115 fruit flies

100 fruit flies





Based on the results the fruit flies liked the ginger ale the most because its is one of the sweetest and has the second most sugar out of all the liquids. Even though apple juice has more grams of sugar than ginger ale I think fruit flies liked the ginger ale because of the carbonation. The fruit flies like the carbonation because it’s a chemical reaction of carbon dioxide and when there is carbon dioxide in the air it helps them detect fruit so thy know that fruit is nearby.

One source of error may be that my count might be off because they are moving creatures and it is hard to count them when there moving around.

One thing worth mentioning is fruit flies often like red wine. Fruit flies love Red wine even though it does not have as much sugar as some of the other liquids. The fruit flies like red wine because of the fermentation/alcohol. Fermentation is when a chemical reaction happens in food, and it is caused by molds, yeast, and bacteria. Fermentation is what happen to create beer and wine. Fruit flies are very attracted to the yeast. According to “Red wine is like crack cocaine for fruit flies.” They love bruised or damaged fruit which is the starting process of fermentation. However, in my experiment they were not as attracted to the red wine because they had other sugary liquids that they preferred.

In conclusion when you need to get fruit flies out of your house capture them with ginger ale or apple juice. If I were to do this experiment a second time, I would use fruit flies with wings in a natural infestation and test the best method to catch fruit flies using different fruits that were fermenting.

This helps people by saving them money therefore, they can catch the most fruit flies and not have to throw the fruit away.   





This helps people by saving them money therefore, they can catch the most fruit flies and not have to throw the fruit away.  It also helps if you are allergic to fruit flies, you can catch more of them by using Ginger Ale or apple juice so you do not have an allergic reaction.

This helps people in warmer climates and through warm summer months as fruit flies become a common indoor pest. Having a cheap and effective way to catch fruit flies is helpful when your fruit is fermenting or becoming brown because of the fruit flies. This is a easy and efficient way to catch them due to the reason that you can use recyclable materials around your house.

Sources Of Error

Sources of Error

In my experiment, I had to count moving, living creatures. I counted the number of fruit flies multiple times before I wrote down the number, however some of the results of a day might be off count by a few fruit flies. I tried to make the exact number but when the fruit flies where moving to different places it was hard to tell if I counted them or not. 



Wu, Katherine J. (July 17, 2018).  How Fruit Flies Stay Young at Heart.   Retrieved from


MedicineNet, Apple Cider Vinegar


Michael F. Potter, Extension Entomologist, University of Kentucky College of Agriculture, Fruit Flies,,moist%20film%20of%20fermenting%20material


Harris, Dominique. FRUIT FLIES...HOW TO GET RID OF THEM, NATURALLY,, On July 14, 2015


Dubin, Alesandra. How to get rid of fruit flies with these easy tips,, May 18, 2018, 1:41 PM Biology of Fruit Flies,


mobile.fatsecret. Ginger Ale, Chianti Wine, apple juice, apple cider


Walmart. Canada Dry® Ginger Ale 355 mL Cans, 12 Pack, SunRype Pure Apple Juice, FLY TYPES & FACTS,


Keith930. Four out of Five Fruit Flies Agree: Red Wine is Better,, Saturday January 05, 2013 · 1:37 PM


Grant. Bonnie. L, Certified Urban Agriculturist, Basil Plant And Flies: Does Basil Keep Flies Away?,, Researchers Find New Taste in Fruit Flies: Carbonated Water,,too%20ripe%20and%20potentially%20toxic.&text=This%20makes%20sense%2C%20they%20say,no%20nutrition%20to%20the%20fly., Wednesday, August 29, 2007


NIH/National Institute on Deafness and Other Communication Disorders, Scientists at the University of California, Berkeley, who conducted the study, Fruit Flies Prefer Fizzy Drinks,,flies%20are%20repelled%20by%20it, August 31, 2007


Geige. Pete, University of Arizona Department of Biochemistry and Molecular Biophysics General Biology Program for Science, The Berg Lab,


PRENGAMAN. KATE, Fruit flies show why swatting at flies is often fruitless,, 4/11/2014, 8:30 AM, Fruit Fly Facts & Information,



I want to thank my mom for helping me stay focused and get all my work handed in on time. I feel I worked harder and did a better job because of this. I would also like to thank my teachers and Ms. Burkell teacher for helping me go through my projects and fixing some mistakes and helping me to figure out what else I could do to make my project better. I would like to thank my friends who also got into CYSF as well. Even though we are competing against each other they still helped me make my experiment the best it could be with ideas and support. One last person to thank is my Dad. He helped guide my to attach my video onto my platform.  He also let me use his Garage for my experiment when the fruit flies were in the terrarium.