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Identification & Distribution:

Adult apterae of Forda formicaria vary in colour from off-white to dull yellow to various shades of dark green or bluish-green. The primary rhinarium on the base of antennal segment 5 is very large, transversely long and extending around the segment. It is 4-5 times larger than the primary rhinarium on antennal segment 4 (this distinguishes it from most other Forda spp. which have the primary rhinarium on the base of antennal segment 5 almost circular and less than 2.5 times larger than that on antennal segment 4). The body length of Forda formicaria is 2-3 mm.

Alates migrating from the primary host have a black head and thorax and a green-yellow abdomen.

 

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In the Mediterranean region and south-west Asia, Forda formicaria forms half-moon-shaped galls on its primary host Pistacia spp. (pistachio). Alates leave the galls in September to November, and move to the roots of numerous grasses and cereals where they found colonies. In many other parts of the world (northern Europe, parts of Asia and North America), host alternation (and sexual reproduction) have been lost, and they live on the roots of grasses all year round. Forda formicaria are always attended by ants, and often live within ants' nests.

 

Other aphids on same host:

Paul (1977)  found at least 16 other aphid species recorded on grass roots in Britain: Anoecia corni,  Anoecia furcata (= A. nemoralis), Anoecia major, Anoecia (Paranoecia) pskovica Mordvilko, Anoecia vagans (= Anoecia willcocksi), Anoecia zirnitsi, Aploneura lentisci,  Baizongia pistaceae (=Pemphigus cornicularius), Forda formicaria, Forda marginata, Geioca setulosa, Geioca utricularia, Paracletus cimiciformis, Rhopalosiphum insertum,  Smynthurodes betae and Tetroneura ulmi. 

Acknowledgements

Our particular thanks to David Fenwick www.aphotofauna.com  for his images of Forda formicaria.

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

  •  Paul, R.G. (1977). Aspects of the biology and taxonomy of British myrmecophilous root aphids. PhD thesis. Imperial College, London.