Scanning electron micrograph, tinted green, of the bird cherry aphid, Rhopalosiphum padi (also known as Aphis avenae), next to its recently cast off exoskeleton. It is seen feeding on barley (Hordeum vulgare). The exoskeleton is made of inelastic chitin which is shed 5 times before adulthood to allow growth. This species is an economic pest, transmitting two viral diseases, yellow dwarf virus & maize leaf fleck virus, which infect crops such as oats, barley, wheat & maize. Transmission occurs when the aphid inserts its proboscis & feeds on sugar stored in the leaves (as here). Large infestations cause the leaves of a plant to wilt & fall. Magnification: X 14 at 35mm size. Original is BW print Z295/048.