Shield bug

A visitor dropped by the other night during nightshift- a magnificent green shield bug, posing on the toilet door and waving its antennae in a friendly manner. This offered a chance to get it to know it better and try to classify it amongst the 50 British species.

Shield bugs are true bugs (Heteroptera) with sucking mouthparts, membranous wingtips and hardened proximal wingparts. Sometimes known as 'stink bugs', they emit an almond-flavoured cyanide compound when threatened. I did not want to annoy my friend, so did not test this.

My friend was of the Pentatomidae family, and almost certainly Palomena prasina, the common green shield bug. It's phytophagous (sap-sucking), with those amazing mouthparts (example from a milkweed bug, right) carried under its head and thorax. Its early instars (juvenile forms) feature even more attractive colouring with black spots on the emerald wingshields, but the adult becomes more brown and drab as summer becomes autumn. They are allegedly sparsely distributed in Scotland, so I was privileged to receive my visit.

Pics from http://www.gwydir.demon.co.uk/ and http://www.salk.edu/

Links
http://www.earthlife.net/insects/shldbugs.html
http://www.nhm.ac.uk/nature-online/life/insects-spiders/fathom-bugslife/assets/26feat_its_a_bugs_life.pdf
http://thevista.co.uk/index.php?page=msc_0227-10-05_Shield_Bugs
http://www.nationalinsectweek.co.uk/resources/buzz_shieldbug.pdf#search=%22Palomena%20prasina%22
http://www.amonline.net.au/factsheets/true_bugs.htm
http://www.gwydir.demon.co.uk/insects/pentatomidae.htm