The spotted-wing drosophila (Drosophila suzukii) is native to Southeast Asia. Its geographical dispersion is very fast and is now widespread throughout large areas in North America, Central America and Europe. Unlike other vinegar flies Drosophila suzukii attacks healthy fruits and therefore it is a serious economic threat to many soft fruit and orchard crops with losses ranging from 5% to 100%.
Female D. suzukii use their serrated ovipositors to lay eggs under the soft skin of fresh and unripe fruits, causing small scars. After 2 days the tissue around a scar softens and collapses, forming a remarkable lesion. From these lesions fluids may exude which attract secondary pests and diseases such as the common vinegar fly D. melanogaster and Botrytis. The period of medium to high risk is from mid spring till late fall.
The adults are approximately 2 to 3 mm in length. Their bodies are yellow-brown with darker bands on the abdomen and have red eyes. The males have a dark spot near the tip of their wings. Females do not have the spotted wing but are recognized by their serrated ovipositor. Eggs are small, translucent white and glossy. The larvae are white, cylindrical and around 3 to 4 mm in size. Pupae are brown-red colored and about 2-3 mm long. D. suzukii has a life cycle of 1 to 2 weeks and produces 10 to 13 generations per year. Their optimal temperature is around 20°C, but they tolerate conditions from 0°C to 30°C. Adults can live about 3 to 9 weeks. They do hibernate, but this is not the case in areas with mild winters. An emerged and fertilized female deposits 2-3 eggs per insertion and is able to produce up to 300 eggs during her life span. The potential population size is huge; after 3 generations around 25 million adults emerge!