Scanning electron micrograph of a peach/potato aphid, Myzus persicae, feeding. The picture is a close view of the aphid's head, showing the stylet (red) at the tip of the rostrum, penetrating a leaf surface. The stylet is about 3microns in diameter; 100x thinner than a hypodermic needle. The insect feeds from phloem, the tissue that transports sugar from the leaves; and xylem, that carries water up from the roots. Phloem sap, driven by osmotic pressure, enters the aphid's gut via the stylet. If the plant is infected with a virus, this may be transferred by the stylet to the next plant the aphid visits. M persicae infests a wide variety of plants, including crop species. It is an economically important vector in the spread of virus diseases, including beet western yellow virus, BMYV, in both sugar beet and winter oilseed rape; beet mosaic virus, BMV, and potato virus Y, PVY