and you had to get your perfectly manicured nails damaged prising them apart.
That is why some pilots always carried a nail file to prise open the bugs.
A Boeing test pilot in 1977 told me that in the Boeing 737-200 the original "Bug" was the moveable orange coloured triangular cursor on the ASI which was designed as the autothrottle cursor. He said that the width of that flat part of the cursor was such that it equalled five knots either side of the pointy end. I thought that was rather neat. So approaching at Vref +5 you simply ensured the ASI needle was aligned with the top end of the orange cursor. It was only valid at the lower end of the speed scale as the speed graduations were different at the higher end of the ASI.
Now Boeing use two white index moveable bugs and squeeze them together in order to depict Vref. The two white index pointers when squeezed together are supposed to average Vref. I prefer that Vref be depicted by one white index pointer personally. Not very good IMHO.. OMG - I must get a life away from Pprune...