Various species
- Symptoms: Aphids are nearly transparent, softbodied sucking insects (picture at left). When present in sufficient numbers, aphids can cause yellowing and premature death of leaves. They exude drops of sugary liquid known as "honeydew", which may cause tiny scorch marks on the foliage and tends to encourage the development of sooty molds. The feeding of Schizaphis graminurn (picture at right) is especially damaging, resulting in the development of necrotic areas sometimes accompanied by purpling and rolling of the infested leaves. The feeding of Diuraphis noxia produces long white stripes on the leaves (picture below), leaf rolling, postrate growth habit, and sterile spikes.
- Life Cycle: The life cycles of aphids involve winged (slates), wingless (apterous), sexual, and asexual forms. When feeding on cereals, the females of most aphid species reproduce asexually (without being fertilized), giving rise to nymphs rather than eggs.
- Hosts/Distribution: Species commonly found on cereals throughout the world include:
* Rhopalosiphum padi
* R. maidis
* Sitobion avenae
* Schizaphis graminurn
* Metopoliphiurn dirhodum
* Diuraphis noxia - Importance: Aphids are important and widespread pests on cereal crops. When feeding in sufficient numbers, they can cause significant damage. In addition, the species listed above may act as vectors of barley yellow dwarf virus.
