Leaf miners are known as larvae of the dipterous insect belonging to the genus Liriomyza. They scrape tunnels in leaves and have become a serious problem in various vegetable and ornamental crops.
With their ovipositor female adults pierce round holes in the upper surface of the leaf to extract plant sap. These feeding spots already reduce the aesthetic value of the plant, especially in ornamental crops. The larvae do not only dig tunnels in the leaves which leads to a reductionin photosynthesis, but can also cause withering or early shedding of the leaves. Feeding spots can also be an entrance for all kinds of diseases.
An adult female measures 2-3 mm. She is black with a yellow ventral surface and legs, and a conspicuous yellow dorsal spot. A male is a little bit smaller. He does not have an ovipositor and for its feeding he relies on the presence of feeding spots made by the females. In such punctures a female can also deposit an egg. The tiny egg is oval and creamy white. Immediately after hatching, a young larva starts eating its way through the leaf. There are three larval stages. In the first stage, the larva is transparent, but later, it turns dirty-white to yellow-ochre and reaches a length of around 2 mm. Just before pupation, the larva cuts a hole in the leaf cuticle and wiggles its way out to pupate. The pupa is yellow to reddish- brown. It may remain on the leaf or drop off. The development time from egg to adult depends on temperature and it takes 2 weeks at 30°C (86°F) and 7 weeks at 15°C (59°F). An adult female lives for 1-2 weeks and is able to lay total several hundreds eggs.
Three species of Liriomyza occur: the tomato leafminer (Lyriomyza bryoniae), the serpentine leafminer (L. trifolii) and the pea leafminer (L. huidobrensis).