Hemiptera- cicadas, aphids, planthoppers, leafhoppers, and shield bugs
"The Hemiptera are called 'true' bugs because everyone - entomologists included - tend to call all insects 'bugs'. That is a loose term, whereas the true bugs are just those contained within the insect order Hemiptera."
"all of them have piercing mouthparts with which they can suck the juices from plants or animals - usually plants. Their mouthparts are contained in a beak (or rostrum) which is usually held underneath the body when not in use."