I’m a big fan of a Dutch singer-songwriter called Spinvis. I love the way he makes the Dutch language singable. One of his songs describes an open day at a care home and it’s called (I translate) ‘Wasps on the Apple Tart’. So even when it’s a lovely day, the sun is shining and visitors are coming, there are wasps on the apple tart. I always think of the expression ‘a fly in the ointment’. I’ve always known that it meant a minor irritation that spoils success or enjoyment of something. But I never realised it was a bible quote. Ecclesiastes 10:1: ‘Dead flies cause the ointment of the apothecary to send forth a stinking savour: so doeth a little folly him that is in reputation for wisdom and honour.’
Flies appear more often in idioms. ‘I’d love to be a fly on the wall’ for that conversation. And gone are the days of nipping off for a fly (secret, sneaky) cigarette, which would have made your boss lose their temper, or ‘fly off the handle’. But we can still ‘fly by the seat of our pants’ or make it up as we go along.
A person can be fly, as in cunning or devious. But fly can also mean cool. First used in the 1930s, it came back into fashion in the Shaft era. And if you really are fly, you won’t be caught ‘flying low’ (with your fly (gulp) open).