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Aphis hypochoeridis

Cat's-ear root aphid

Identification & Distribution  Biology & Ecology 

Identification & Distribution:

Apterae of Aphis hypochoeridis are bright yellow to pale greenish yellow. The abdominal dorsum is entirely pale (see first picture below) or with dusky bands across tergites 7-8 only. The siphunculi are dark. They are 3.5-7.1 times their midlength diameters, and 0.9 to 1.6 times the length of the elongated pale or dusky finger-shaped cauda. The body length of Aphis hypochoeridis is 0.7-1.6 mm.

The Aphis hypochoeridis alate (see second picture above) has marginal and postsiphuncular sclerites, dusky bands on tergites 7-8, and median sclerites on a variable number of tergites 1-6. They have 5-8 secondary rhinaria on antennal segment III and 0-4 on antennal segment IV.

The cat's-ear root aphid lives on the root collar, the underside of radical leaves and up the lower part of the stem of Hypochaeris radicata (Cat's Ear). Aphis hypochoeridis do not host alternate. They have a sexual stage in the life cycle with oviparae and males appearing in autumn. They are usually 'tented over' (with earth) by Myrmica or Lasius ants (see below). Aphis hypochoeridis is widely distributed in Britain and throughout Europe.

 

Biology & Ecology:

Aphis hypochoeridis one of the easiest root aphids to find since they are nearly always attended by ants. The ants 'tent over' the aphid colony, the basal root collar, and the stem of their foodplant (cat's ear, Hypochaeris radicata) with soil particles (see first picture below).

 

In 2014 we found several colonies of Aphis hypochoeridis on cat's ear (the cat's ear flower is second picture above) growing on the grassy bank outside a neighbour's house.

In this case the colonies were attended by Myrmica ants. The picture above shows one of these attending the aphids on the plant's root-collar.

The aphids may have orange patches laterally and near the siphunculi. The nymphs tend to be more yellow than the more greenish apterae.

 

The globules of liquid in several of the pictures above are aphid honeydew. This sugar-rich liquid is excreted by the aphids and fed upon by the attending ants. The relationship between the ants and aphids is mutualistic - the ants get a rich energy source and the aphids gain protection from predators.

Acknowledgements

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).

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