Preventing fruit fly infestations
A simple trap using vinegar
Juanita Powell went away for two weeks and forgot to do the deed.
The Truro resident didn’t empty the compost bin under her kitchen sink and came home to literally swarms of fruit flies.
Her sister has also had an infestation of fruit flies. Powell said, when this happened, she kept the vacuum handy with pantyhose and elastic over the end of hose. When she’d spy a fruit fly, she’d turn on vacuum, whip off pantyhose, vacuum up fly, then put the hose back on to keep them trapped in vacuum bag.
Fruit flies seem so easy to attract and yet so difficult to get to leave. But does it have to be that way?
Marlene Snyder was a professor of genetics for 37 years, with 25 of those years at Acadia University. While at Acadia, she often used fruit flies as a teaching tool because of their short life span — around two weeks from an egg to an adult capable of laying eggs.
Prior to her time at Acadia, Snyder spent 10 years working in a lab devoted to understanding the development of multi-celled animals, which includes both fruit flies and humans.
“Although it is hard for people to believe and to understand, essentially all our developmental pathways have their nearly exact counterpart in fruit flies, derived from an ancient common ancestor to us both,” said Snyder.
We share the genes for essentially all the major developmental stages of our lives. So, using fruit flies to study development gives not only a better understanding of the intricacies of the flies, but also a deeper understanding of human development, she explained.
ARE FRUIT FLIES HARMFUL?
Other than an annoyance, fruit flies pose essentially no health hazard for people, assured Snyder.
“There is the very unlikely possibility that they will have encountered something bad for us just prior to interacting with us, mostly because they are attracted to surfaces and sources of food that are not toxic to us,” said Snyder.
WHAT ATTRACTS FRUIT FLIES?
According to Snyder, fruit flies are attracted to volatiles that are the result of fermentation, such as ethanol, like the alcohol we drink.
They are also highly attracted to volatiles from fruit — the lovely scent of bananas — especially over-ripe bananas; the volatiles from lemons and limes; and any other source of a volatile from lightly rotted fruits and vegetables, she explained.
These volatiles are the result of yeast fermenting the sugars found in food.
They are not attracted by meats — either fresh or rotting.
KEEPING FRUIT FLIES AT BAY
There is one simple way to keep flies to an absolute minimum, according to Snyder, noting that simple is not necessarily easy. That is to keep an immaculate kitchen.
• There should never be cans or bottles (of beer or wine especially, but also fruit juice or pop) left unrinsed on a counter.
• There should never be compost left in the kitchen for longer than a day. Instead, collect the compost that is produced during the day and remove it from the building.
• There should never be dirty plates, pots and pans, or utensils left out. Wash them or put them in the dishwasher and run the dishwasher.
• There should never be counters that are not thoroughly cleaned.
• The stove top should be cleaned daily.
• Any fruits or vegetables should be stored in the refrigerator. Never leave limes, lemons or bananas on a counter.
• If you want to have bananas in the house, don’t buy more than two at a time and eat them within two days.
Following this sort of cleaning plan during fruit fly season will virtually eliminate the problem, says Snyder.
MYTHS FOR PREVENTING FRUIT FLIES
There are many other suggested hacks out there, but Snyder said they have limited use.
For example, some suggest washing fruit when you bring it home. Washing fruit might remove flies, eggs or larvae that are present on the fruit when it comes into the house and so is not a bad idea, agreed Snyder. But, it would take quite thorough washing, not just a rinse off, so it is probably impractical and won’t help if there is another source of flies.
Others say to keep the kitchen drain clean. Snyder said although keeping drains clean might be helpful in removing a source of fermenting food, drains are not the main place that flies would inhabit, so it is probably of limited use.
WHAT TO DO
Instead, if flies become a problem, you can make a simple fly trap by putting a few drops of dish detergent into a narrow mouth jar, along with some water and a little vinegar or a wedge of lemon, says Snyder.
Place a funnel in the mouth of the jar, with its tip above the surface of the liquid. The flies will be attracted by the scent. The detergent keeps them from being able to walk on water, which they can easily do. The funnel makes it tricky for them to fly out, so they are more likely to be caught in the liquid.
I follow my own advice pretty closely about the clean kitchen, but, even so, I almost always need to make a trap once in a while, says Snyder. But I also like the flies!
“So, I enjoy the season when they are around; I just try to keep them at a minimum,” she said.