Lessons From A Fruit Fly Infestation

Posted by: Mary Small

Colorado Master Gardener State

Coordinator

Are tiny flies driving you buggy? Several kinds are common indoors, so it’s really important to capture and identify them. It helps you figure out why they are there in the first place, how long they might stay and most important - how to manage them.

The Small household recently had the un-delightful company of fruit flies. I knew they were fruit flies because I’d captured a couple and identified them.  The insects are attracted to fermentation odors, such as that found with over- ripe or decaying fruit, beer, wine and sugary drinks. Fruit flies are quite small (1/16”), often have red eyes and are very annoying!

I observed they seemed to be concentrated around the ripening bananas on the kitchen counter. “Okay,” I thought, “once the bananas are gone, they will be too.” I even took the peels outside immediately after eating the fruit, thinking that would quickly decrease the fruit fly population. Nope! Bananas gone, still finding fruit flies. 

Next I constructed a funnel trap. This consists of a jar with either cider vinegar or a piece of ripe fruit in the bottom.  Set a funnel (metal, plastic or one made from a small piece of paper) over the opening to the jar, narrow side down. Make sure the outer edge of the funnel fits the opening of the jar fairly well. Then tape the funnel to the jar along the junction where the two met. You don’t want anybody escaping!

By Downtowngal (Own work) [CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons

 Fruit flies are attracted to the fermenting fruit/vinegar and crawl or fly down the funnel to get to the prize. But then they can’t get out and die, falling to the bottom of the jar. My trap worked like a dream – I was trapping quite a few every day. My hope was that the trap would collect the remaining flies (assuming they arrived on the bananas) and the infestation would be over. 

While the trap was in place, I checked for and wiped up anything that looked like a spill from the pantry shelves, counter tops and refrigerator. I was also fanatical about taking empty drink bottles outside to the recycle bin right after consumption. I hoped this would reduce potential food sources, but instead I had an annoyed family along with the fruit flies!

One day while hunting up a particular spice, I noticed an odd smell coming out of a cupboard that I apparently hadn’t searched very well.  I’d caught a whiff a couple of times before, but it was very faint. This time, it was stronger and so a more thorough search ensued. Shoved into the far back corner in a plastic bag, I found three small rotting potatoes. In addition to being disgusting, they turned out to be the source of the fruit flies. After disposing of the culprits, it only took one trap refresh to take out the remaining flies.  

And now, there’s a new location to store and readily observe the condition of potatoes so we don’t have unwanted company again. So far, so good!