Because of their short gestration period and their relatively low number of genes, Fruit Flies are favorites for genetic research.

Visited my Nephew ( Michael Levine ) at his Lab, and I saw a fruit fly with legs on its head instead of antennas, due to gene modification.

The Tiny Fruit Fly Is a Giant of Scientific Research

Drosophila melanogaster, the fruit fly, is one of the most important model organisms in scientific research. Dan Tracey, a professor of biology at Indiana University, told us why—and the explanation will surprise you.

https://endpoints.elysiumhealth.com/model-organisms-drosophila-melanogaster-fruit-fly-928de0046a9c

Why use the fly in research?       

https://www.yourgenome.org/facts/why-use-the-fly-in-research

Benefits of the fruit fly

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• The relationship between fruit fly and human genes^? is so close that often the sequences of newly discovered human genes, including disease genes, can be matched with equivalent genes in the fly.
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• 75 per cent of the genes that cause disease in humans are also found in the fruit fly.
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• Drosophila have a short, simple reproduction cycle. It is normally about 8-14 days, depending on the environmental temperature. This means that several generations can be observed in a matter of months.
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• Fruit fly are small (3 mm long) but not so small that they can’t be seen without a microscope. This allows scientists to keep millions of them in the laboratory at a time.
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• They are inexpensive to maintain in the laboratory.
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• They require a simple diet consisting of simple sources of carbohydrates (cornmeal) and proteins (yeast extract).
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• The only care they need is having their food changed regularly (every 10-14 days at 25˚C or 5-6 weeks at 18˚C).
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• Drosophila have ‘polytene’ chromosomes, which means that they are oversized and have barcode-like banding patterns of light and dark. During early Drosophila research scientists could therefore easily identify chromosomal^? rearrangements and deletions under the microscope. 
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• It is relatively straightforward to mutate (disrupt or alter) fruit fly genes.
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• The fruit fly provides a simple means of creating transgenic^? animals that express certain proteins^?, such as the green fluorescent^? protein of jellyfish.
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• The long and distinguished history of research devoted to the study of the fruit fly means that a remarkable amount is now known about its biology. 
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