Eriococcus coriaceus (Blue Gum Scale)

Eriococcus coriaceus is a common pest of Eucalyptus trees, particularly E.globulus in plantations.  The oval sac covers the body of the wingless female.  The female lays hundreds of eggs within the sac.  There is always an opening left at the end to allow nymphs to leave the capsule.  The honeydew exuded by the insects often causes a black sooty mould to grow on the leaves which can affect photosynthesis.  There are many natural predators and parasites of this species.  These include ladybird beetles and parasitic wasps.

Eriococcus coriaceus
Late December 2004
Knocklofty Reserve, Hobart

Late January 2012
Mount Wellington
 

Early August 2016
Knocklofty Reserve, Hobart

Mid March 2018
Knocklofty Reserve, Hobart

Various aged colonies on a Eucalyptus globulus
Late August 2020
Knocklofty Reserve, Hobart
       

Early March 2021
Tasmanian Bushland Gardens
Note that they are being predated upon by the larvae of the gumtree scale ladybird Rhyzobius ventralis
IMG 8749 2  IMG 8749

Mid March 2021
“Inala”, Lunawanna, Bruny Island
IMG 9021


References

CSIRO, 1990. Insects of Australia, Volume  1: A Textbook for Students and Research Workers. 2nd Edition. Melbourne University Publishing.

Forest and Timber insects of Australia No 22.  https://www.scionresearch.com/__data/assets/pdf_file/0018/3951/Ent22Eriococcuscoriaceus.pdf  Accessed September 18, 2016