Periphyllus obscurus

Identification & Distribution:

The adult aptera of Periphyllus obscurus is rather small and blackish green. The terminal process of the antenna is 3.2-6.9 times the length of the base of the last antennal segment. The hind tibiae are more or less pale throughout (cf. Periphyllus testudinaceus  which has tibiae with a contrasting dark base and distal section). The siphunculi are dark and only about as long as the basal width. The cauda is rounded with a constriction near its base and is more than half as long as its basal width. The body length is 1.8-2.6 mm.

The dark periphyllus aphid is found in ant-attended colonies on young shoots, leaf petioles and undersides of leaves of field maple (Acer campestre). Aestivating nymphs are not produced, and all stages are present through the summer (cf. Periphyllus testudinaceus  which spends mid-summer as aestivating nymphs). The second picture above shows a colony of Periphyllus obscurus in early August. Note that apterae and nymphs of several stages are present together - at this time of year, Periphyllus testudinaceus would normally only be present as aestivating nymphs. The very young nymphs of Periphyllus obscurus are green, whilst older nymphs are brownish. Oviparous females and males are produced in the autumn. Periphyllus obscurus is found in central and western Europe.

Biology & Ecology:

Periphyllus obscurus is usually (or always) attended by ants as shown in the picture below where it was vigorously protected by southern wood ants (Formica rufa).

Quinet (1997)  recorded it as being attended by Lasius fuliginosus (see picture below).

Other aphids on same host:

Blackman & Eastop list 22 species of aphid  as feeding on field maple (Acer campestre) worldwide, and provide formal identification keys.

Of those aphid species, Baker (2015)  lists 18 as occurring in Britain: Aphis craccivora,  Aphis fabae,  Aulacorthum solani,  Drepanosiphum acerinum,  Drepanosiphum aceris,  Drepanosiphum dixoni, Drepanosiphum platanoidis,  Mimeuria ulmiphila, Periphyllus acericola,  Periphyllus aceris,  Periphyllus bulgaricus, Periphyllus californiensis,  Periphyllus hirticornis,  Periphyllus minutus, Periphyllus obscurus, Periphyllus testudinaceus,  Stomaphis graffii and Stomaphis longirostris.

Damage and control

Periphyllus obscurus seems to be rather uncommon in UK so is unlikely to reach pest numbers. In Europe, however, it is clearly more abundant and has been recorded as a pest species on ornamental trees and shrubs by Ripka (1999) in Hungary. The rather small colony in the picture below was being predated by a syrphid larva.

Identifications & Acknowledgements Whilst we make every effort to ensure that identifications are correct, we cannot absolutely warranty their accuracy. 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  Dixon, A.F.G. & Thieme, T. (2007). Aphids on deciduous trees. Naturalist's Handbooks 29. Richmond  Quinet, Y. et al. (1997). Food recruitment as a component of the trunk-trail foraging behaviour of Lasius fuliginosus (Hymenoptera: Formicidae). Behavioural Processes 40(1), 75-83. Abstract   Ripka, G. (1999). Növénykárosító ízeltlábúak a díszfákon és a díszcserjéken: pajzstetvek, levéltetvek, atkák. (Arthropod pests of ornamental trees and shrubs: scale insects, aphids, mites). Növényvédelem 35(12), 623-626.  Abstract   Stroyan, H.L.G. (1977). Homoptera: Aphidoidea (Part) - Chaitophoridae and Callaphidae. Handbooks for the identification of British insects. 2 (4a) Royal Entomological Society of London. Full text