Hi Fellas,
It's not always that easy with Shieldbugs, I have found Hawthorn Shieldbug on almost every species of tree and bush that bears berries. Other Shieldbug species can be found on many species of tree and plants that aren't mentioned in the Textbooks.
There is very little modern literature on identification, the last book being the Land & Water Bugs of the British Isles. 1959. Copies are now selling at £125 upwards. A CD-ROM version is available from Pisces Conservation at about £55.00.
A good alternative for the Shieldbugs and a few closely related species is The Shieldbugs of Surrey by Roger D. Hawkins published by the Surrey Wildlife Trust, in hardback at £15.00. 2003. ISBN 0 9526065 7 7. Good Keys, emergence tables and lots of other goodies are included.
Surrey is probably the best county in Britain for Shieldbug species and I would certainly recommend this book to anyone interested in them. Good colour pictures of all the species, and their nymphs, that you are ever likely to come across elsewhere in Britain includes some possibly extinct species as well.
Before anyone asks I am not on a commission for sales, (more's the pity) lol.
Nor is it because one of my 'papers' gets a mention.
Harry.