Corn Leaf Aphid

The bodies of wingless parthenogenetic females are green or whitish-green. The head, antennae, legs, cornicles, tail, and transverse bands on the abdomen are black-brown. The body has sparse short hairs. The length of the antennae is less than half the length of the body. Cornicles are not longer than the finger-like tail. In winged females, the head and thoracic section are black-brown and the cornicles are shorter than in the wingless females. Most R. maidis populations are anholocyclic, i.e. reproduction occurs entirely by parthenogenesis. However, sexual reproduction has been reported in Pakistan and Korea, with Prunus ssp. as the primary host. In populations in Japan and Kenya, males but not sexually reproducing females have been found.

In winter, winged parthenogenetic females and larvae survive on wild-growing monocots, from which they move to agricultural fields in the spring. Fields populate gradually, starting from the edges to the center. Reproduction is rapid, with up to twelve generations per year. The aphid population reaches a maximum late in the summer. Dense populations of R. maidis on maize (Zea mays) can cause direct damage through the removal of photosynthates. Large amounts of honeydew that is deposited by aphid feeding on maize tassels can prevent pollen shed and decrease yield by up to 90%. Several damaging maize viruses, including Maize yellow dwarf virus, Barley yellow dwarf virus, Sugarcane mosaic virus, and Cucumber mosaic virus, are transmitted by R. maidis. In addition to feeding on maize, R. maidis infests a variety of cultivated grasses, including wheat, barley, oat, rye, sorghum, sugarcane, and rice. Barley is a particularly suitable host for R. maidis, though there also is considerable within-species variation in resistance.