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Identification & Distribution:

Adult apterae of Thelaxes suberi vary in colour from pale green to dark brown (see pictures below). The terminal process of the sixth antennal segment is 0.26-0.40 times as long as the base of that segment. The body length of adult aptera is 0.9-1.5 mm.

 

Thelaxes suberi siphunculi are very short and the knob of the cauda is at least as long as broad (see the first micrograph below of adult aptera in alcohol). The hairs on abdominal tergite 5 are mostly more than 25um long, very thick and dagger-like (see between the siphunculi in the second photomicrograph below).

 

Thelaxes suberi live on the young shoots, leaves and developing acorns of Quercus spp. especially Quercus cerris and Quercus ilex (but not Quercus robur). Immature sexual forms apparently appear at the beginning of the summer, aestivate through the summer, and then adult oviparae and males occur in autumn. Thelaxes suberi is present in England, southern Europe, Mediterranean region, southwest Asia and South Africa.

 

Biology & Ecology:

We have only found this species once, on holm oak growing in a churchyard on the South Coast of England.

Mifsud et al. (2009)  reported that Thelaxes suberi was frequent on Quercus ilex in the Maltese Islands, and often occurred concurrently with Hoplocallis picta  and Myzocallis schreiberi.  We have also found both these latter species on holm oak in southern England, although not with Thelaxes suberi.

Much like the related Thelaxes dryophila,  Thelaxes suberi is often attended by ants.

 

 

Damage and control

Species of Thelaxes have been reported to cause economic damage to ornamental oaks (Alford, 2012 ).

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 

References

  • Alford, D.V. (2012). Pests of ornamental trees, shrubs and flowers: a colour handbook. Second Edition. Academic Press.

  • Mifsud, D. et al. (2009). Present status of aphid studies in Malta (Central Mediterranean) with special reference to tree dwelling species. Redia 92, 93-96. Full text