Fruit flies are small insects commonly found in association with over-ripened or rotten fruits and vegetables. There are approximately 1,500 known species in the genus Drosophila (Markow and O'Grady 2006).
A few species of fruit fly such as the spotted-wing drosophila, Drosophila suzukii (Matsumura), can infest un-ripened fruits and are therefore of major economic significance.
They were first detected outside their original habitat in Japan and other parts of South-Eastern Asia in the US in 2008, and since then has been found in numerous countries around the world becoming a serious threat to fruit crops.
Within Europe, this species is also widely distributed in Austria, France, Italy, Spain, Germany, The Netherlands, Switzerland, and in 2012 was found in the UK.
Drosophila suzukii adults are small (3–4 mm) yellowish-brown flies with red eyes. The adults have a pale brown or yellowish-brown thorax with black bands on the abdomen. The antennae are short and stubby with branched arista. Males have a distinguishing dark spot along the front edge of each wing. Spotless males are also possible, but are rarely observed in the field and should be verified by a taxonomist for positive identification. In addition, males have two rows of combs on each fore tarsus which are absent in females.
Drosophila suzukii prefers a moderate climate but can also survive in cold conditions (Kanzawa 1939). The flies are most active at 20°C (68°F). Activity becomes reduced at temperatures above 30°C (86°F) or below freezing.
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