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Acidia cognata

In English there are two fly families referred to as Fruit Flies: Tephritidae and Drosophilidae. The name Fruit Fly however is best applicable to the fly family Drosophilidae to which the Common Fruit Fly belongs. The Fruit Flies in the family Tephritidae are small flies, usually no bigger than 10 mm. They are often very colourful and the wings are always pictured. Because of this they are among the only small flies readily identified. The females have a pointed rear, which is used to bore into the leaf or stem of a plant. The egg or eggs are deposited in this opening. After hatching most larvae live inside a leaf, which they mine, or inside the stem of a plant. Of some species however the larvae are parasitic. The family is represented by some 3,000 species world wide and includes some serious pest insects in agriculture.

Measuring 6 to 7 mm Acidia cognata is a rather big species. It is an orange fly with a yellow head and an intriguing pattern of black or brown markings on its wings. Adults are on the wing from May to the end of September, occasionally later. Females make an opening in the leaf of the host plant and deposit one egg in the opening. The larva lives as a miner inside the leaf. The mines are blotchy and may occupy a big part of the leaf, especially when two or more larvae meet and continue in the same leaf. When the larva is full frown it pupates and overwinters in the soil. A few food plants are known, but usually the larvae mine the big leaves of Butterbur and Colt's foot. This is a common species all over Europe, including Britain and Ireland.