Schizaphis graminum

Definition

A cosmopolitan aphid species (family Aphididae, order Hemiptera) commonly known as the greenbug or wheat aphid, obligately associated with grasses (family Poaceae). Adults are small, pale green to yellowish, with a dark green dorsal stripe and short, dark-tipped siphunculi. The species is a major pest of cereal crops worldwide, causing direct damage through phloem feeding and indirect harm as a vector of barley yellow dwarf virus and other luteoviruses. Populations exhibit host-adapted biotypes and include several recognized subspecies.

Etymology

Genus from Greek schizein (to split) + aphis (aphid), referring to the forked cauda; species epithet from Latin gramen (grass), denoting its grass-feeding habit

Example

In Kansas wheat fields, Schizaphis graminum biotype E outbreaks are monitored using suction traps to time insecticide applications before economic thresholds are reached.

Synonyms

• Greenbug
• wheat aphid

Related Terms

• Aphididae
• Hemiptera
• Biotype
• siphunculus
• barley yellow dwarf virus
• Poaceae
• holocyclic
• anholocyclic

Usage Notes

The common name 'greenbug' is widely used in North American agricultural literature, while 'wheat aphid' predominates in European and Asian contexts. Host-specialized biotypes (e.g., biotypes B, C, E, I) are morphologically cryptic but differ in virulence on specific wheat cultivars and in reproductive performance on alternative hosts. Subspecies designations (e.g., S. g. agrostis, S. g. gigjai) reflect geographic and host-association variation but are not universally accepted in taxonomic practice.