Green’s Dictionary of Slang

(Aus.) the Tasmanian equivalent of the Victorian bogan n. (1)

1990		Mercury (Hobart) 28 May 15/1: Chigger, or Bogan – a rough and unsavoury person.
2003		Aus. Word Map 🌐 Having lived most of my life in Hobart I can confirm that the term chigger is in widespread use. Further that it stems from a suburb by the name of Chigwell. It has however been widened to potentially encompass any young person, male or female that appears to be of a lower socio-economic status. Chigwell was originally a Housing Department suburb.
2006		Bulletin 12 Sept. 🌐 But in Boon’s home state of Tasmania, they’re ‘Chiggers’ - in honour of the reputedly bogan suburb of Chigwell.