Mrs. Earwig is an arrogant, snobbish witch. She pronounces her name "Ah-weej", but is the only one who does. She is married to a retired wizard Dr Earwig, and is of the kind of witches who read books, and has even written several books on "magik", the "k" is to distinguish what she considers the True Craft from the everyday stuff of Granny Weatherwax et al. Although she does use practical folk wisdom as a witch, she focuses mainly on crystals and other items considered useless by witches of Esmeralda Weatherwax's tradition. She wears a great deal of "occult" jewelry that doesn't actually do anything. (Not that Granny doesn't recognise the uses of Boffo in creating a suitably witch-like personna; however using it and believing in it are two different things.) Granny Weatherwax dislikes Mrs. Earwig, claiming that she reduces witchcraft to "shoppin'". Needless to say these two are intense rivals, and treat each other with hostile politeness. She is a great one to organize things, especially those that don't need to be organized, like other witches. She is the chairwoman of the Witch Trials committee, initially organizing a trophy and awards ceremony but giving up on this after Granny Weatherwax wins it.
She promotes witchcraft among younger girls by selling her various books including First Flights in Witchcraft, My Fairy Friends, and To Ride a Golden Broomstick, in addition to an unnamed book on "Flower Magick". These are widely denounced by other witches as being ridiculous nonsense that only appeals to those who don't know what witchcraft is really about. Her approach to teaching appears to be to trust the folk wisdom of the locals when it comes to practical things like birthing and medicine, (never a good idea as Annagramma finds out) and focus on such things as crystals, magic circles and soothing chants to help matters along. Her first, last, and only, trainee was Annagramma Hawkin but her 'skill' as a mentor becomes obvious when Annagramma goes out on her own and fails completely until Tiffany and her friends come to her aid and teach her 'real witching'. In The Shepherd's Crown, she believes that she is the rightful heir to Granny Weatherwax and hopes to take over as the head witch (if witches ever had a leader) after her death. Not surprisingly she is mortified when Tiffany Aching is chosen and initially she does everything she can to try to get the other witches to reverse this decision. Once the battle with the elves is imminent, however, she becomes a useful ally, particularly because her complete self-absorption makes her completely immune to Elven Glamour, which creates human self-doubt. Her husband Dr. Earwig is mentioned in Unseen Academicals as one of the few wizards who have retired (although he technically just left to get married, which, according to Mustrum Ridcully, is the same as dying).
Letice Earwig's character is most likely inspired by any number of real-world Wiccans, witches and neopagans. In particular, parallels are drawn between Earwig and Wiccan author Silver RavenWolf, author of To Ride a Silver Broomstick. RavenWolf is generally strongly disapproved of as "fluffy" by the vast majority of Wiccans and witches in the real world, much as Mrs Earwig is strongly disapproved of and considered woolly by Discworld witches and wizards. Both Earwig and RavenWolf are seen to be pandering to teenagers who want to play at being dark and mysterious by becoming witches, but without any real content behind them. The use of the 'ostentatious variant spelling of the word magic as 'Magik' in her book title is reminiscent of such new age witches as Alister Crowley as well as many modern 'Wiccans'. Her character also has many similarities to both Sybil Trelawny and Gilderoy Lockhart in JK Rowling's Harry Potter series, but as Pratchett has pointed out "we are all working from the same well here"..
Her name resonates with the term for a listening device that is placed in the ear, appropriate given that she thinks highly of herself and is always giving others advice on how to be a better witch. That device takes its name from the myth that earwigs like to hide in human ears. Her given name Letice, resonates with the garden salad green lettuce which is also slang for money - an appropriate connotation given that Mrs. Earwig is an author, a bit of a charlatan and clearly, as Tiffany points out to her, above going around the poor neighbourhoods of her steading to help the less fortunate. Mrs. Earwig pronounces her name 'Ah-wij' which resonates with the Monty Python sketch which Pratchett has used before about the man whose name is 'Throat Warbler Mangrove' but it pronounced 'Raymond Luxury Yacht' which itself is a takeoff on British names like Featherstonehaugh and Cholmondeley that are pronounced Fanshawe and Chumley respectively, nothing like they are spelled. Her pretentious name pronunciation is also possibly a reference to Mrs Bucket from the British sitcom 'Keeping up Appearances'. The character who has middle class pretensions insists that her name is actually given a French pronunciation - 'bouquet'. Alternately, with the pronunciation 'Ah-wij" Letice or her husband (witches don't normally take their husbands' names) could be from Quirm.