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Identification & Distribution

Aphis crepidis lives in ant-tented colonies on various species of hawk's-beard (Crepis) (see first picture below). The apterae are dark bluish-green to yellow-green, and are not wax powdered (see second picture below). The dorsum of the aptera is membranous apart from a rather faint short dusky spinal bar on tergite 8. The marginal tubercles on tergites II-V of Aphis crepidis are prominent, and are bluntly subconical to hemispherical in shape. The femoral and proximal tibial hairs are shorter than the least width of the tibia, whereas the outer apical hairs of the hind tibia may equal that width. The siphunculi are dark. The cauda is dusky and bears 6-11 hairs (cf. Aphis hypochoeridis which has 4-8 caudal hairs). The body length of Aphis crepidis is 1.2-2.0 mm.

Alate Aphis crepidis (see third picture above) are a rather dull green with marginal and postsiphuncular sclerites and dusky bands on tergites VII-VIII. Aphis crepidis is very closely related to, and apparently morphologically indistinguishable from, Aphis taraxacicola which feeds on dandelion, not hawksbeard.

The micrographs below show an adult aptera Aphis crepidis dorsal and ventral in isopropyl alcohol.

The hawksbeard root aphid lives in ant shelters (see first picture on this page, and second below) at the base of rough hawksbeard (Crepis biennis), smooth hawksbeard (Crepis capillaris) and beaked hawksbeard (Crepis vesicaria). It does not host alternate and sexual forms have been found in September. Stroyan (1984) reports that Aphis crepidis is very little known in Britain (only Cambridge and Derby), but comments that the species is perhaps overlooked, a common problem for all the root feeders. It has recently been reported from Wales (Baker, 2009) and now (our own observations) from several locations in East Sussex, West Sussex and Hampshire. Aphis crepidis is found throughout Europe, apart from the north, and extends into Iran.

 

Biology & Ecology:

Life cycle

We first found Aphis crepidis at Rye Harbour in East Sussex, where the host plants of Aphis crepidis, smooth hawksbeard (Crepis capillaris, see first picture below) and beaked hawksbeard (Crepis vesicaria, see second picture below), are common on old shingle ridges and near the edge of salt marsh areas.

The winged dispersive forms (alatae) are produced in June and July, in somewhat larger numbers than is usual for root aphids.

We have since found the aphid through the summer in a variety of xeric habitats, from pavements in suburban areas to forest tracks. We have yet to find the sexual forms but the species is known to produce oviparae and males in autumn. Eggs are laid on the basal leaves of Crepis.

Colour

The colour of live adult apterae ranges from dark blue-green to pale green, in each case mottled with darker patches.

Immature Aphis crepidis (see picture below) are a markedly paler green than the adults.

 

Ant attendance

All the colonies we have found were attended by the common black ant Lasius niger (see picture below).

Baker (2009) found Aphis crepidis feeding sheltered and attended by Lasius niger on basal and subterranean parts of Crepis capillaris growing on amenity grassland at Cardiff Bay, Wales. He also found the same species on subterranean and rarely the upper parts of a Crepis species growing beside a pebble beach at Barry, Wales.

Baker (pers. comm.) has recorded Lysiphlebus fabarum as a parasitoid of Aphis crepidis in Wales. Barahoei (2014) has recorded Aphidius matricariae as a parasitoid of Aphis crepidis in Iran.

 

Other aphids on same host:

Acknowledgements

We especially thank Rye Harbour Nature Reserve for their kind assistance, and permission to sample.

Whilst we make every effort to ensure that identifications are correct, we cannot absolutely warranty their accuracy. We have mostly made 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

  • Baker, E.A. (2009). Observations of aphids (Aphidoidea) new to Wales. British Journal of Entomology and Natural History 22, 235-246. Abstract

  • Barahoei, H. et al. (2014). Checklist of Aphidiinae parasitoids (Hymenoptera: Braconidae) and their host associations in Iran. Journal of Crop Protection 3(2), 199-232. Full text