They are sharp on my macbook.Tack sharp or Macro sharp No but its not a macro lens or tack like primes and they are heavily cropped.They where shot in raw 1/250 F8 @ ISO 220 - 320 - 500 at 300mm its in the Exif info if you look.
Thanks for posting the settings. I did not follow your link, just saw the images here, which is why I asked for the settings.
Like I said, maybe it's just compression I am seeing on my end. I believe you when you say that they are sharp.
I think they are nice images, and I commend you for getting anywhere near them. I would never get near enough to get these shots, usually I m the one running the other way.
#2 is my fave of the bunch, I think it has the best composition of the three and I like that the bee is facing us. I wish I could see the other wing but completely understand it was outside of your control.