Going on vacation is one of the most beautiful parts of summer, but it also means not tending our gardens for days or even weeks. I was recently on a weeklong trip that saw multiple thunderstorms. When I got back I saw that a lot of my tomatoes had flaked off from the rain. With the rain came a fruit fly infestation, like a real storm from them.
Fruit flies are a common late summer pest both outdoors and indoors. Fruit flies are attracted to the smell of ripe and fermenting fruits and vegetables and are a difficult problem to prevent. In this blog, we're going to cover some ways to manage them in the garden and get rid of fruit flies in your home.
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Fruit fly overview
Drosophila fruit flies are the most common in most U.S. gardens. Source: Gailhampshire
The common fruit fly Drosophila melanogaster is also known as the vinegar fly because of its attraction to the pungent smell of ripe fruit and vegetables. Drosophila melanogaster is just one of many species of fruit flies in the genus Drosophila. Fruit flies are attracted to certain aromatic compounds that send signals to their antennae and are believed to have come from sub-Saharan Africa. Adult fruit flies can be between 3-4 mm long and have yellow or brown bodies and distinctive red eyes. Adult flies have two antennae with three segments each that end in tiny hairs. Fruit flies are sexually reproduced and any female fly can lay up to 100 eggs per day and 500 eggs in their lifetime.
Fruit fly life cycle
Fruit flies have very short life cycles of 8-10 days from egg to adulthood, depending on the temperature. They are particularly active in summer and practically disappear when it gets cold. Their rapid rate of reproduction makes fruit flies the perfect species to use in scientific laboratories for various genetic experiments, and they have made the lead in at least nine Nobel Prize-winning studies!
Fruit flies go through a complete metamorphosis. Each fruit fly begins with an egg, which then hatches into a three-stage larva. The larvae grow and molt at each stage, then become a pupa and finally hatch as an adult fruit fly. Adults quickly become sexually active after leaving their pupae and can begin mating within 24 hours.
Fruit flies lay their eggs in damp places, often in or on fermenting fruits. Both fruits and vegetables can be habitats for these pests, especially when they decompose. It is not uncommon to find fruit flies in a compost heap near fermenting products. Female fruit flies lay up to 500 eggs during their lifetime. With such a short life cycle, it means multiple generations of them can appear in a single season.
Common living spaces
Have you ever heard of the saying, "Time flies like an arrow and fruit flies like a banana?" It turns out that while fruit flies are attracted to bananas, they have a stronger predilection for citrus fruits, especially when the time is right to lay their eggs. The fruit fly, which we all know today, is a generalist and can be found on many common foods. They are also commonly found on unpicked ripe fruit outdoors along with other insects such as the citrus fly.
However, scientists searching for the origins of the fruit fly traced its human relationship to a South African fruit called marula (Sclerocarya birrea), loved by human tribes and kept in their cave houses. Marula is a very sugary fruit with a highly fermentable pulp and a staple food for these tribes. Researchers suspect that in this way fruits fly and people became commensal or “eat from the same table”.
What do fruit flies eat?
Fruit flies are not fussy eaters and feed on almost anything. Despite their name, fruit flies are flexible to consume a variety of foods in addition to fruits, including onions, potatoes, and even dew secreted by aphids, to name a few. The fruit fly larvae feed on the yeast that is produced by rotting plant material.
How to fight fruit flies
Xanthaciura fruit flies are found in the southeastern United States. Source: Judy Gallagher
Fruit flies are very difficult to control because they reproduce very quickly and are widespread. They are one of the most common food contaminants for farmers, grocers, and restaurants. Even if your home doesn't have fruit flies, you can inevitably take home a piece of fruit or vegetable that contains eggs or larvae that will hatch and reproduce in your home. However, some hygiene best practices can help keep the population down and get rid of fruit flies whenever possible.
Organic or chemical control
Organic spray, like horticultural oil, can be used to either kill adult flies or prevent eggs from hatching. Bio-sprays are not as effective against adults as the liquid must come in contact with the flies to be effective. Use sprays regularly to mitigate the rapid generation of these flies.
Chemical sprays are more likely to be used in orchards and commercial operations. They may not be specific to fruit flies and can harm other beneficial insects. Farm managers use a combination of techniques such as the use of glue traps or sex pheromone traps to monitor the population of adult fruit flies and to spray the fruit. These methods are used in addition to general hygiene practices.
Fruit fly traps are a common method of environmental control. They are commercially available or can be easily made from household materials. A simple and effective fruit fly trap is to fill a glass with a few inches of apple cider vinegar, beer, or wine and add a few drops of dish soap. The flies are attracted to the smell of the fermenting liquid. The soap breaks the surface tension of the apple cider vinegar and fruit flies fall in and drown. Place the trap near susceptible fruit and dispose of the solution with the flies every few days.
You can make a similar fruit fly trap by placing a bait like a piece of banana or a bit of apple cider vinegar on the bottom of a mason jar and creating a paper funnel that sits on top of the jar. Fruit flies can fly into the fruit fly trap, but not fly out. You can also combine these two methods to increase the efficiency of your fishing technique!
Preventing fruit flies
One of the most important elements in controlling fruit flies is eliminating their breeding grounds. Indoors, this means cleaning up the trash in your home, mopping up spilled sugar, throwing away rotting fruit and onions, and cleaning your drains and garbage disposal frequently. Don't forget beer cans, wine bottles, and cider bottles and cans!
If possible, refrigerate the products as fruit flies cannot develop in cold temperatures. When making your own jam, kombucha, or other fermented foods and condiments, follow hygienic best practices and keep your jars sealed tight. Just like the master gardeners, many government advisory services also have master food preservers who can provide help and guidance on how to preserve food at home.
When outdoors, it is important to keep the garden or orchard tidy. Save any fruit that has rotten or visible fly infestation. For products like tomatoes, you can harvest them before they are fully ripe so they don't split and spoil on the vine.
If you're composting, putting a tarp over your pile or a cover on your compost bin can reduce access to overripe produce near the top of the pile. It can also help heat the compost, and high heat can kill the larvae and eggs, as well as any adults trapped in the heat.
frequently asked Questions
Ceratitis spp., Also called Mediterranean fruit fly or medflies, can be a nuisance. Source: jeans_Photos
Q: What's the fastest way to get rid of fruit flies?
A: The quickest way to get rid of fruit flies is to eliminate their food source and breeding ground. That means keeping surfaces inside and outside free from rot or overripe products. If they cannot reproduce, they cannot produce the next generation of insect pests.
Keep garbage disposal and drains clean and free of vegetable or fruit residues. Store food immediately to prevent adults from laying eggs on the surface. Keep the trash cans closed to avoid infestation.
Q: What is it that attracts fruit flies to humans?
A: Fruit flies are food generalists who are attracted to many of the foods that humans grow and consume. Scientists believe that the fruit fly-human relationship developed about 10,000 years ago when people started eating and storing a South African fruit called marula, and that fruit flies were originally food specialists that only fed on marula fruit.
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