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Genus Phorodon

Hop aphids

Species Overview: Genus Phorodon  Phorodon humuli 

Genus Phorodon [Macrosiphini]

These are medium-sized aphids on winter hosts (2.0 - 2.6mm long), but smaller on summer hosts. They are generally green and adult viviparae may be winged or wingless. They have characteristic pointed projections on the inside of the antennal tubercles. The siphunculi are pale, medium length, thicker at their bases and slightly curved outwards at their tips. The cauda is short, pale and blunt. Winged forms have has a black patch of fused cross bars on the upper surface of the abdomen.

A small genus of only 4 species in Europe, north Africa, and south-west Asia and introduced to North America and New Zealand. They have a sexual stage in the life cycle. Some alternate between the primary host of Blackthorn and Plum (Prunaceae) and the secondary host, Hops (Cannabidaceae). Others feed only on the secondary hosts. They are not attended by ants. One species is the main pest on hops causing damage directly and through virus transmission.

 

Phorodon humuli (Damson - hop aphid)

Identification:The apterae are small to medium sized, whitish to pale yellowish green and relatively shiny. The abdomen is marked with three dark green longitudinal stripes. The head has the characteristic pair of elongate projections on the inside of the antennal tubercles. The siphunculi are pale with slightly dusky tips and over twice as long as the pale cauda. Body length is 2.0-2.6 mm on plum and 1.1-1.8 mm on hop.

 

The damson-hop aphid host alternates from blackthorn or plum (Prunaceae) to hops (Cannabinaceae). It does not cause leaf curling itself but often lives on plum leaves distorted by Brachycaudus helichrysi. Migration of winged forms to hops takes place from late spring. There is a return migration to the winter hosts in September where sexual forms are produced and eggs laid. It is indigenous to Europe and neighbouring areas, but has been introduced to North America and New Zealand.

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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).

Useful weblinks 

 

Identification requests

Alan Outen, 26 May 2014, aphid query from Clifton, Beds

The species below (all individuals less than 3mm) was on leaves of Wild Damson also at the Recreation Ground of Clifton, Beds. Though I have had what seems to be the same thing on the Victoria Plum in our garden. Would I be correct in thinking these are Phorodon humuli rather than Hyalopterus pruni, or are the images not good enough/ specimens too immature to be sure? I think am correctly seeing the elongate projections on the inside of the antennal tubercles (which I assume is not a feature of the Hyalopterus sp.) and there is no sign of any mealyness.

Image(s) copyright Alan Outen,  all rights reserved.

   

Bob, InfluentialPoints:

  • [These] are indeed Phorodon humili. The pointed projections on the antennal tubercles are very distinctive.