Are Wingless Beetles considered an 'Insect'

Do they fit the criteria of an insect e.g. having a head, thorax and abdomen?

Please explain.
Thank you.

Beetles form around 40% of all insects and are therefore the biggest insect group, with around 350,000 species in total. All beetles start life as grubs and then form a pupa and metamorphose into their adult form. Most adult beetles can fly, although a few, such as glow-worms and weevils, have lost the ability

http://www.bbc.co.uk/nature/life/Beetle

What would you classify them as then? Sometimes organisms are born with oddities not common amongst their species. A wingless beetle is as much an insect as a person born without wisdom teeth is still human.

hope this helps
:)

Not all beetles have wings...
Beetles are considered an insect, and a wingless beetle definitely is a beetle..So yes, wingless beetles are insects.