There is no sense in it. In Chaucer's time a symbol for lechery was the sparrow, in Shakespeare's the polecat, in our own the ram. The reason for these changes is obscure.
Even more puzzling is our pointless discrimination against some forms of insect. Lice and fleas are equally hard to live with, yet a contemptible person is often called a louse, never a flea. Indeed, fleas are held up as models of fitness. 'Dung-beetle' has become a popular insult lately, but I have never heard anyone calling an enemy 'spider', though spiders are not nearly as handsome as beetles.
The test of a good insult is its aptness. 'Ratbag', vividly evocative once, has now become so general that it can mean almost anything ('A person to whom some opprobrium attaches' - Australian National Dictionary). It is mild by Australian standards; like 'bastard', it can almost be used in the neutral sense of 'a person'. If you call a woman a cow it means no more than that you don't like her. Is she devious? Call her a 'snake'. Dirty, unkempt? Call her, if you must, a 'haybag'. The most inappropriate insult, come to think of it, is 'animal'. Indignantly applied to terrorists who do things no animal would dream of doing.Reuse content