New Brunswick

How to deal with pesky — but scientifically helpful — fruit flies

With fruit flies swarming kitchens this time of year, biologist Stephen Heard explains how to keep the pesky insects out and how to get rid of them.

A female fruit fly can lay 200 to 500 eggs during the few weeks she's alive

Biologist Stephen Heard says fruit flies may be pesky to most people, but scientists use them for genetic research. (Gary Moore/CBC)

Fruit flies aren't limited to a specific season, but the pesky bugs tend to swarm inside houses this time of year, searching for food and warmer temperatures. 

The flies are only about a millimetre long and are attracted to ripe fruit, vegetables and compost — making kitchens a popular landing spot. 

Biologist Stephen Heard of the University of New Brunswick says people tend to notice fruit flies more during the summer and fall. 

"They're going to try and move somewhere better, and looking for the resources they need to lay their eggs and have their larvae develop."

Heard, of the University of New Brunswick, says fruit flies are drawn to kitchens this time of year looking for warmer temperatures and ripe fruit. (Gary Moore/CBC)

Heard said it's tough to stop fruit flies from getting inside because they're so small, but making the kitchen a less attractive destination will help slow them down. =

"So if you've got a pile of bananas sitting on the counter, look for the ones that are super old and it's time to make a smoothie with them. 

Heard says a homemade fruit-fly trap is easy to make and the best way to get rid of the insects. (Gary Moore/CBC)

"If you have a lot of fruit or vegetable peelings that are in your garbage can or in your compost bin, time to move those outside."

A fruit fly's lifespan is a few weeks, but in that short cycle a female can lay between 200 and 500 eggs. With that kind of reproduction fruit flies can linger and be a nuisance.

Fruit flies are a common annoyance in kitchens when fruit and vegetables are left out, so University of New Brunswick biology professor Steve Heard explains how to trap and get rid of the little pests. 0:54

But Heard said it's not too hard to get rid of the flies and recommended an easy way to make a funnel trap — similar to a small lobster trap — using a jar, paper, soap and something that has a fruit smell, such as cider vinegar.

"Make a paper funnel and tape that into the mouth of the jar, just like the narrow bit in a lobster trap, so the fly can find its way in but can't easily find its way out."

Heard said the fruit smell will lure the flies into the trap. Using a trap or two for a week on the kitchen counter will take care of most of the flies. 

Important for genetic research

As annoying as fruit flies might be around the house, scientists bank on them for genetic research. 

And that's because the genetic makeup of fruit flies is quite similar to humans. 

An adult fruit fly, about a millimetre long, is studied under a microscope. (Gary Moore/CBC)

"Virtually all your biochemistry, virtually all your metabolism is happening in those flies as well."

Since fruit flies are so plentiful, with a short life cycle, they're really easy to study, according to Heard.

"We can grow a generation — hundreds and thousands of flies through a generation in a week." 

About the Author

Gary Moore

CBC News

Gary Moore is a video journalist based in Fredericton.

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