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Aphidinae : Schizaphis agrostis
 

 

Schizaphis agrostis

Bent-grass aphid

On this page: Identification & Distribution Other aphids on the same host

Identification & Distribution

Feeding on grass by Schizaphis agrostis results in conspicuous and characteristic feeding damage to its host, Agrostis species. The leaves turn red or yellow-brown and eventually die off (but note some Agrostis species have naturally reddish stolons). Such feeding damage can be seen in the picture below of a colony of Schizaphis agrostis. The adult apterae are grass-green to yellow-green, with a darker green median dorsal line. Antennal segments I, II and the basal part of III are pale, but the other segments are dark. The antennal terminal process is 2.8-4.0 times as long as the base of antennal segment VI. The apical rostral segment (RIV+V) is 0.75-0.88 times the length of the second hind tarsal segment (HTII) (cf. Schizaphis graminum, which has RIV+V 0.65-0.80 times as long as HTII, and cf. Schizaphis holci, which has RIV+V 0.80-1.00 times HTII). Marginal tubercles are present on abdominal tergites I & VII. The siphunculi and cauda are pale, but the former have a dusky apices. The siphunculi are 1.3-1.5 times the caudal length (cf. Schizaphis holci, which has siphunculi 1.25-1.4 times the length of the cauda). The body length of adult Schizaphis agrostis apterae is 1.4-2.0 mm.

Image above copyright Ed Baker, all rights reserved.

Alatae of Schizaphis agrostis are greenish brown with indistinct abdominal marginal sclerites. Their antennae bear 4-10 secondary rhinaria on segment III, and 0-2 on segment IV. The siphunculi are thinner than in the apterae.

Schizaphis agrostis feeds on a limited number of grass species, mainly velvet bent (Agrostis canina), creeping bent (Agrostis stolonifera) and various meadow grass (Poa) species, especially on plants growing in very dry, sandy spots, as well as in salt marshes or saline meadows. Hille Ris Lambers (1953) found often quite large colonies on the uppersides of leaves, where the aphids usually sit in single rows with their heads towards the stems. They are sometimes ant attended. Alatae are formed in the third generation. Sexuales have been found in October with alate males. The overwintering eggs are laid on the leaves and stems of the host grass species. Schizaphis agrostis is found in northern and central Europe, possible extending to Siberia, and has apparently been introduced to North America.

 

Other aphids on the same host

Blackman & Eastop list 11 species of aphid as feeding on velvet bent (Agrostis canina) worldwide, and provide formal identification keys (Show World list). Of those aphid species, Baker (2015) lists 10 as occurring in Britain (Show British list).

Blackman & Eastop list 28 species of aphid as feeding on creeping bent (Agrostis stolonifera) worldwide, and provide formal identification keys (Show World list). Of those aphid species, Baker (2015) lists 26 as occurring in Britain (Show British list).

Acknowledgements

We are very grateful to Ed Baker who sent us the picture above of a colony of Schizaphis agrostis on the grass Agrostis stolonifera in his front garden.

We have made provisional identifications from high resolution photos of living specimens, along with host plant identity. In the great majority of cases, identifications have been confirmed by microscopic examination of preserved specimens. We have used the keys and species accounts of Blackman & Eastop (1994) and Blackman & Eastop (2006) supplemented with Blackman (1974), Stroyan (1977), Stroyan (1984), Blackman & Eastop (1984), Heie (1980-1995), Dixon & Thieme (2007) and Blackman (2010). We fully acknowledge these authors as the source for the (summarized) taxonomic information we have presented. Any errors in identification or information are ours alone, and we would be very grateful for any corrections. For assistance on the terms used for aphid morphology we suggest the figure provided by Blackman & Eastop (2006).

Useful weblinks

References

  • Hille Ris Lambers, D. (1939). On some Western European aphids. Zool. Med. Museum Leiden 22, 79-119. Full text