Drosophila melanogaster and D. simulans (Diptera: Drosophilidae)—morphological differences

Sturtevant (1919) wrote “In the course of genetic experiments with Drosophila melanogaster Meigen a wild race was found that gave unexpected results. Examination showed that it was structurally different from typical D. melanogaster. The new form has been found to be common and widely distributed. Since it is evidently a distinct species that has hitherto been overlooked, and since it will certainly be extensively discussed in genetic literature in the future, the following name [Drosophila simulans] and description are presented.” Indeed, one hundred years later, this species pair continue to fascinate. They are, in most parts of the world, among the most frequently encountered insects in our kitchens and gardens, they are readily attracted to fermenting fruit, but they do not cause fruit to rot like D. suzukii. In North America the common name, for both, is Fruit Fly, but in Australia and New Zealand Fruit Fly is the common name for the pest species of Bactrocera (Tephritidae). The high-resolution diagnostic images presented here highlight the important morphological characters that are useful for identification.