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Fruit flies are small insects that, as their name implies, often are found in and feed on fruits, although they like other foods, too. Falling into two main categories, they prefer to eat matter that is decaying or fermenting, and most varieties are fairly tiny. They are found around the globe and reproduce extremely quickly, which has given them a significant role in research despite their reputation as a nuisance. Many varieties get into buildings simply by finding small cracks and holes to slip through, but they also get transported from place to place in less-than-ideal produce. People typically can get them under control by keeping homes free of rotting items and by using homemade or purchased traps.
There are two major groups of fruit flies: Drosophilidae and Tephritidae. The first family is thought to have around 1,500 individual species, while experts estimate the number for the second at roughly 5,000. The actual number is likely much higher, because researchers have yet to identify them all.
The vast majority of fruit fly species are quite small, with adult flies usually measuring somewhere between 0.08 to 0.2 inches (2 to 5 millimeters) long. Certain types, however, can be extremely large by comparison, looking more like regular house flies. Most varieties in the Drosophilidae family are reddish to reddish brown in color with clear wings. Ones classed as Tephritidae typically have more colorful wings, with some people referring to them as "peacock flies" as a result.
Where They're Found
These bugs can be found all over the world, and they live in many different climates. Warm, tropical climates host more kinds, however, because they tend to promote a sufficient supply of vegetation while also making it easy for organic matter to decay. They usually can spread very quickly from area to area, because most species are excellent fliers that are capable of traveling several miles in a single day.
Although some species of fruit flies have preferences for particular foods, in general, they usually feed on any decaying matter, especially rotting fruits and vegetables. More specifically, they like the yeast that breaks down the sugar in these items during the fermentation process. As this decomposition occurs, the yeast produces the byproduct of alcohol, which many species also enjoy — incidentally, the preference for alcohol is also why they tend to congregate around wine and beer bottles, and why they are sometimes a problem in bars and restaurants. Some researchers, such as biologist Dr. Todd Todd Schlenke of Emory University, believe that consuming the alcohol helps ward off parasites, affecting the development of enemy eggs and making the flies less attractive to attack.
Even though these insects typically prefer fruits and veggies, they often can be found in other rotting material, including meats and even the scum that forms in drains. Some have adapted, becoming predators or parasites, and many kinds also eat sap and flower nectar. Their ability to eat such a wide range of foods is largely what makes them so difficult to get rid of, and why most people see them as a nuisance. In some cases, they have an extremely negative effect on agriculture, ruining entire crops, but only a few hundred of the thousands of species are considered a serious threat — some varieties actually have been used as a biological tool to control other insects.
Reproduction and Life Cycle
In general, fruit flies lay their eggs in whatever foods they're eating. Depending on the species, a single female can be capable of laying up to 500 eggs, and she can mate more than once during her life cycle. These eggs usually hatch in less than a day, sometimes within just a few hours. After this point, they progress through the larval stage, which usually lasts around four days, and which can be further divided into three separate phrases that include molting. They then enter the pupal stage, where they grow their wings and legs. Finally, they emerge as fully-grown adults, and the process, which typically takes 14 – 30 days, starts all over again.
Where They Come From
Some individuals believe that, because these bugs eat decaying matter and some of the byproducts of the fermentation process, their presence indicates a dirty home or building. This isn't always the case. With their great sense of smell and tiny bodies, they easily can maneuver into a kitchen from outside through window screens, door jams or any other crack. They sometimes catch a ride in grocery bags or hatch from eggs laid in less-than-fresh food brought home from a grocery store.
Getting rid of any old, rotting foods is a good start to eliminating fruit flies, as is keeping fresh fruits, vegetables and meats in the refrigerator instead of out in the open. Some non-food items, such as wet mops, dirty dishes and old sponges, hold small particles of decaying material, too, however, so they generally need to be cleared from a home, as well. Consistently wiping down counters often helps.
If any insects remain after a thorough cleaning and even with proper food storage — this sometimes can happen if they are living in a drain, for example — a person easily can trap them. Commercial traps are available, but homemade traps are often cheaper and can be just as effective. People who want to make one at home just need to put a paper funnel in the mouth of a jar or bottle that has some wine, beer, decaying fruit or vegetables or yeast and sugar in it. The bugs will enter the funnel to reach their feast and will not be able to find their way out.
Use in Science
Despite annoying many people, these tiny insects have made a gigantic name for themselves in the field of science. In particular, the common fruit fly, Drosophila melanogaster, has been invaluable to the field of genetics. Its short, ten-day life cycle, avid ability to reproduce and large chromosomes make it an ideal choice for laboratory experiments in heredity.
Fruit flies have been a source of fuel for the creation versus evolution debate. Creationists, who generally oppose the widely accepted theory of evolution, claim that the use of these insects in the laboratory, specifically the attempt to create new species through the mutation of chromosomes, has yielded no surviving results. Evolutionists rebuke the claim with the fact that fruit flies have too few chromosomes to provide an evolutionary advantage when manipulated. Basically, evolutionists hold that the bugs are successful just as they are and have no reason to change.