Bugs (Hemiptera)
To the layman a bug is merely any small insect or other invertebrate, but technically it really refers to a much narrower (though still very diverse) group of insects, the order Hemiptera. Included within this order are 'typical bugs' (e.g. shieldbugs), leafhoppers and their allies and a group that includes aphids, psyllids and whiteflies.
I have lots more material to be added to this section in due course, but for now just a small selection...
Heteroptera: typical bugs
Auchenorryncha: leafhoppers and allies
Stenorryncha: aphids, sacle insects, whiteflies and jumping plant lice