Printed

A Photographic Guide to the Shieldbugs and Squashbugs of the British Isles by Martin Evans & Roger Edmondson (WGUK in association with WILDGuides, 2005)

A Pocket Guide to the Shieldbugs & Leatherbugs of Britain & Ireland by Bryan J Pinchen (Forficula Books, 2009)

Shieldbugs of the British Isles Bernard Nau (FSC WildID Fold-out chart)

Land & Water Bugs of the British Isles by T R E Southwood & Dennis Leston (Warne 1959) is still useful.

Websites

The British Bugs website describes itself as a ‘An online identification guide to British Hemiptera’. It contains superb photos of each species with summary information. The identification route is either through knowing the classification structure of the Systematic lists: Heteroptera, Auchenorryncha and Psylloidea (Sternorrhyncha) or simply by searching for similarity of appearance with the photos in the Gallery. 

Heteroptera of the British Isles Flickr photos: Bob Ryan 

Google Lens: Go to google.com and there is a camera icon at the right of the search bar. Click on this, and you can drag and drop any image and it will do its best to identify it – so can be used for any flora and fauna, vertebrates and invertebrates etc. (as well as buildings, landscapes – anything, in fact.)  Worth a look, but treat identifications with caution!

Apps