The beadle to which Dickens refers is a minor church official in charge of ushering and keeping order during religious services. You'll find the word among the works of other writers, too: Nathaniel Hawthorne in The Scarlet Letter, Chaim Potok in The Chosen, Harper Lee in To Kill a Mockingbird, and Shakespeare in King Lear, for example. (And yes, beadle does sound quite a bit like the winged insects, beetles.)
Charles Dickens has this person called the beadle" in lots of his books. Is that like a nickname for a man with buggy eyes or something?"
From Dickens's Oliver Twist:
"Hold your tongue, Beadle," said the second old gentleman, when Mr. Bumble had given vent to this compound adjective.
In Madame Bovary, by Gustave Flaubert:
One evening when the window was open, and she, sitting by it, had been watching Lestiboudois, the beadle, trimming the box, she suddenly heard the Angelus ringing.
And from Miguel de Cervantes's Don Quixote:
"So be it," answered Sancho. "I say I will know how to behave, for once in my life I was beadle of a brotherhood, and the beadle's gown sat so well on me that all said I looked as if I was to be steward of the same brotherhood."