Green’s Dictionary of Slang

1. a woman, occas. a man, who permits or encourages a good deal of sexual intimacy but not intercourse.

1831		Satirist (London) 7 Aug. 141/2: A cockchafer...Lady Blessington.
1833		‘The Chapter Of Cocks’ in Swell!!! or, Slap-Up Chaunter 36: She was teased too by a nasty cock-chaffer; / But Cock all the way made himself secure, This cock-eyed maid was his cock-sure.
1841		‘The Cockchafer!’ in Gentleman Steeple-Chaser 25: My sweet cockchafer [...] She causes me to rise again / With her hand so lily so white.

2. a prostitute.

1835		G. Kent Modern Flash Dict. 10: Cock chafer – a lady bird, a prostitute.
1837		‘I Have Kissed the Biggest Whore’ in Flash Olio in Spedding & Watt (eds) Bawdy Songbooks (2011) III 189: Tho’ to roger I was born, / Then cockchafers all take care.
1844		New Sprees of London 35: [T]he well known Mother Jones continues her business as usual in Lombard-court [...] She is open at all hours, we believe, and a passable cock-chafer may be found.

3. (UK Und./prison, also chafer) a prison treadmill.

1859, 1860		Hotten Dict. of Modern Sl. etc.
1859		Matsell Vocabulum 18: chafer. The treadmill.
1861		(con. 1840s–50s) H. Mayhew London Labour and London Poor II 51/2: He ‘expiated,’ as it is called, this offense by three month’s exercise on the ‘cockchafer’ (tread-mill).
1865		Leaves from Diary of Celebrated Burglar 144/1: I’d as sooin bee i’ ‘chokey’ on bread an’ water az sit ’ere aul daiy [...] an’ ’sides we’ll be whipped on t’ chaiffir afear t’daiy ’z eouwt.
1870		Hotten Sl. Dict.

4. the vagina.

1890–1904

Farmer & Henley Sl. and Its Analogues.

5. a general term of abuse.

1922		E. Raymond Tell England (1965) 55: Did you ever see an orthodox doctor produce a cockchafer like that?
1949		K. Amis letter 12 July in Leader (2000) 209: I shall swing for the old cockchafer.