E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
At the final overthrow of the Moors, the Castilians made them their servants, and their active habits and officious manners greatly pleased the proud and lazy Spaniards, who called them mi todita (my factotum). Hence a cringing officious dependent, who will do all sorts of dirty work for you, is called a todita or toad-eater.
Pulteneys toad-eater. Henry Vane. So called by Walpole (1742).