Scanning electron micrograph of whitefly eggs and larvae on a tomato leaf. The picture shows a ring of empty egg cases of the glasshouse white fly, Trialeurodes vaporariorum, together with ( 2 o'clock position) one egg (red) that has not hatched. Also visible are elliptical larvae ("nymphs") at varying stages of development (yellow). At the picture edge, to upper right, is a small first instar larva with legs visible.The larger larvae (0.8-1mm long) have lost their legs and are sessile. The egg shells form a ring because the female white fly was feeding as she lay the eggs; piercing the leaf in the middle of the circle, and pivoting herself around her fixed position. Eggs may also be found in semicircles, straight lines or simply at random. T. vaporariorum is a common nuisance in glasshouses. Some whitefly species are serious pests as vectors for pathogens such as begomoviruses.