The following four publications have all been important in my quest to learn about inconspicuous ladybirds.
ROY,H. & BROWN,P. 2018 Field Guide to the Ladybirds of Great Britain and Ireland, London:Bloomsbury Wildlife.
This is now the definitive field guide to conspicuous ladybirds with excellent illustrations by Richard Lewington.
This is also the best available guide to the inconspicuous ladybirds but some lack identification criteria and the illustrations are printed unnecessarily small.
ROY,H., BROWN,P., FROST,R &POLAND,R. 2011. The ladybirds (Coccinellidae) of Britain and Ireland. Wallingford:Biological Records Centre.
Although not mentioned in the title, this is the ladybird atlas. The maps are now a bit out of date but this was my first introduction to the inconspicuous ladybirds, with maps, photos and text for most species.
TELFER,M.G. 2015. Scymnus rubromaculatus (Goeze) in Britain, colour pattern variation in S. interruptus (Goeze) and a key to the British species of subgenus Scymnus sensu stricto (Coccinellidae). The Coleopterist 24(1):1.
When I read this article in 2019 it immediatly sorted out any confusion I had over the status of Dusky Ladybird and filled in one of the last pieces of the jigsaw.
It also confirms the presence of the pale form of Red-flanked Ladybird in the UK.
ROY,H.E., BROWN,P.M.J., COMONT,R.F., POLAND,R.L. & SLOGGETT,J.J. 2013. Ladybirds (Naturalists' Handbooks 10), Exeter:Pelagic Publishing.
This is a handbook covering the scientific study of ladybirds. It includes a dichotomous identification key for all species. I find these keys difficult as microscopes are needed if you start at the beginning and if you head straight to the species you suspect, they are not easy to read in reverse.
The following websites are useful.
This is the site for submitting ladybird records and any other wildlife sightings. There are also smart phone apps for record submition, although I have not tried any of these.
A very useful resource, this contains distribition maps for a variety of wildlife, including all the ladybirds.
A Finnish website with good photographs of a variety of interesting inconspicuous ladybird species.
A website covering the beetles of Germany, with a good section on ladybirds.
Follow Mark Hows as he searches for ladybirds and other wildlife in Britain and beyond.
The PDF: A Guide to Micro Ladybirds of Shropshire by Maria Justamond and David W. Williams is excellent.
I haven't been able to make a link but it should be searchable on the internet.
Some recent books covering European ladybirds have helped take my researches further:
Oldrich NEDVED & Milan DJURIC (2022) Ladybirds of Europe, Serbia: Habiprot
A brilliant introduction to all the European species, with maps showing distribution by country, one or more photos per species and very brief notes on identification and or habitats. It gives a very useful overview of what is out there, although further reading and research is then needed to follow up the more difficult species.
Oldrich NEDVED (2020) Ladybird beetles (Coccinellidae) of Central Europe, Praha: Academia
Covering a smaller geographical area than the above guide, this is more detailed
with more photos, technical descriptions and keys.