InfluentialPoints.com
Biology, images, analysis, design...
Aphids Find them How to ID AphidBlog
"It has long been an axiom of mine that the little things are infinitely the most important" (Sherlock Holmes)

Search this site

 

 

Identification & Distribution

Adult apterae of Aphis epilobii are dark blackish-green to reddish-brown (see first picture below) which often appears dark-grey to pinkish-brown (see second picture below) because of a rather uniform powdering of wax (cf. Aphis grossulariae which is dull green to light green with only a light wax bloom). The apical rostral segment (R IV+V) is 1.28-1.55 times the length of segment II of the hind tarsus (HT II) (cf. Aphis grossulariae which has R IV+V 1.42-1.68 times the length of HT II). The abdominal dorsum of Aphis epilobii is membranous with only a dusky narrow band across tergite 8 and sometimes 7. There are small conical marginal tubercles on tergites 1 and 7 (visible if you can expand the first micrograph image below), but not on tergites 2-6 (cf. Aphis grossulariae which has marginal tubercles on most tergites). The siphunculi and basal parts of the antennae are pale, but the cauda is dusky. The siphunculi are 1-1.6 times the length of the cauda. The body length of Aphis epilobii apterae is 1.3-2.1 mm.

The alate (see first picture below) has marginal, postsiphuncular and small marginal sclerites, but no dorsal cross bands in front of the siphunculi. The antennal terminal process is about 3 times the length of the basal part of antennal segment 6. Antennal segment III has 30-32 secondary rhinaria, segment IV has 17, and V has 7-9. Immatures (see second picture below) resemble the adults with blackish-green and reddish-brown forms.

The images below are micrographs of an apterous adult and an alate in isopropyl alcohol.

The ovipara is reddish brown or greenish black with the hind tibia more or less distinctly swollen on the basal half. The winged male (see pictures below) is dark but has an entirely membranous dorsum.

The willowherb aphid does not host alternate. Sexual forms occur in autumn. It feeds on broad-leaved willowherb (Epilobium montanum) or more rarely other Epilobium species. Aphis epilobii is not usually ant attended. It is widely distributed throughout Europe.

 

Biology & Ecology

Life cycle

Aphis epilobii is usually a very common aphid. The overwintering eggs hatch in spring and by late summer most plants of broad-leaved willowherb will have colonies of aphids especially on the growing shoot and flowers (see picture below).

They are often in mixed species colonies with other Aphis species found on Epilobium, especially the host-alternating Aphis grossulariae which overwinters on gooseberry. The picture below shows a mixed species colony of Aphis epilobii (dark green) and Aphis grossulariae (pale green).

By late September they start to produce sexual forms. Oviparae are reddish brown or greenish black with the hind tibiae more or less distinctly swollen on the basal half. The picture below shows a reddish brown ovipara.

Pictures below show (first) several green or brown wingless oviparae and (second) winged males, which were moving up and down the colony seeking suitable mates.

Mating takes place on the drying stems of Epilobium.

The oviparae then lay the shiny black eggs along the dead stems of the host plant shown below.

Ant attendance

Unlike Aphis grossulariae, a species with which they often form mixed species colonies, Aphis epilobii are not usually ant attended. However, we have found oviparae of Aphis epilobii being attended (see picture below).

Natural enemies

By egg-laying time, many of the colony may have been killed by parasitoids which mummify their aphid hosts (see picture below). The form of the mummy suggests Lysiphlebus fabarum is the parasitoid in this case, a parasitoid also reported by Rakhshani et al. (2013).

The mummy of another parasitoid species attacking Aphis epilobii is shown below.

Other parasitoids found attacking Aphis epilobii in Europe are Praon dorsale (Müller et al., 1999) and Praon abjectum and Binodoxys angelicae (Kavallieratos et al., 2004).

Little else seems to have been published about the ecology of Aphis epilobii, although O'Doherty & Ring (1987) found that this species was capable of surviving considerable supercooling. They noted however that this seemed to be a general property of aphids rather than specific to those species encountering such conditions.

 

Other aphids on same host:

Aphis epilobii has been recorded from 13 Epilobium species.

Acknowledgements

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

  • Blackman, R. L. & Eastop, V. (2006) Aphids on the World's Herbaceous Plants and Shrubs. Vols 1 & 2. J. Wiley & Sons, Chichester, UK. Full text

  • O'Doherty, R. & Ring, R.A. (1987). Supercooling ability of aphid populations from British Columbia and the Canadian Arctic. Canadian Journal of Zoology 65(3), 763-765. Abstract

  • Kavallieratos et al. (2004). A survey of aphid parasitoids (Hymenoptera: Braconidae: Aphidiinae) of Southeastern Europe and their aphid-plant associations. Appl. Entomol. Zool. 39(3), 527-563. Full text

  • Müller, C.B. et al. (1999). The structure of an aphid-parasitoid community. Journal of Animal Ecology 68, 346-370. Full text

  • Rakhshani, E. (2013). Tritrophic associations and taxonomic notes on Lysiphlebus fabarum (Marshall) (Hymenoptera: Braconidae: Aphidiinae), a keystone aphid parasitoid in Iran. Arch. Biol. Sci., Belgrade, 65(2), 667-68. Full text

  • 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.