Below are some examples of the most popular identification websites, some of which I have co-authored and others that contain examples of the most common species. It is my intention to add other additional less well-known groups as and when time permits!
Butterflies & Moths
NATIONAL MUSEUMS NORTHERN IRELAND http://www.habitas.org.uk
THE BUTTERFLIES & MOTHS OF NORTHERN IRELAND http://www.habitas.org.uk/moths/
MOTHS IRELAND MAPPING IRELAND'S MOTHS www.mothsireland.com
BUTTERFLY IRELAND www.butterflyireland.com
UK MOTHS OF BRITAIN AND IRELAND ukmoths.org.uk
LIFE HISTORIES OF BUTTERFLIES & MOTHS www.ukleps.org
BRITISH LEAFMINERS www.leafmines.co.uk
Dragonflies
DRAGONFLYIRELAND www.habitas.org.uk/dragonflyireland
BRITISH DRAGONFLY SOCIETY british-dragonflies.org.uk
Beetles
GROUND BEETLES OF IRELAND www.habitas.org.uk/groundbeetles
LADYBIRDS OF IRELAND www.habitas.org.uk/ladybirds
Wildflowers
FLORA OF NORTHERN IRELAND www.habitas.org.uk/flora
IRISH WILDFLOWERS www.irishwildflowers.ie
HARDY ORCHID SOCIETY www.hardyorchidsociety.org.uk
IRISH ORCHID SOCIETY www.irishorchidsociety.org
Lichens
LICHENIRELAND www.habitas.org.uk/lichenireland
IRISH LICHENS www.irishlichens.ie
BRITISH LICHEN SOCIETY www.britishlichensociety.org.uk
Orthoptera
GRASSHOPPERS OF EUROPE www.grasshoppersofeurope.com
Happy DIY Home happydiyhome.com/types-of-grasshoppers/
Fungi
FIRST NATURE https://www.first-nature.com/fungi/~id-guide.php
Slime Moulds