Depends how much spare cash you have. If you could afford, yes. If not, no.
Because the camera does it automatically and you are using PP software that doesn't strip it out as you process, then you don't have to do anything. Your image is carrying all the EXIF data. Just right click on the post above and if you have EXIF viewer software in your browser you'll see an option something like 'View Exif Data' (if you don't see this, you can download a plug-in for your browser).
What I got for your image was:
Camera Maker: Canon
Camera Model: Canon EOS 60D
Lens: EF50mm f/1.4 USM
Image Date: 2012-03-24 12:13:53 +0200
Focal Length: 50mm
Aperture: f/4.0
Exposure Time: 0.0020 s (1/500)
ISO equiv: 100
Exposure Bias: none
Metering Mode: Spot
Exposure: shutter priority (semi-auto)
White Balance: Auto
Flash Fired: No (enforced)
Orientation: Normal
Color Space: Adobe RGB (1998)
GPS Coordinate: undefined, undefined
Software: Adobe Photoshop CS5.1 Windows
Simply right clicking on the image then selecting Image Properties will give the basics. Camera, shutter speed, aperture, Iso.
With regard to the macro lens question; I would agree with Donald that it depends on how much spare cash you have 'burning a hole in your pocket'.
Also, what other lenses do you currently have?
For larger insects like butterflies, I can successfully manage with 24-105, 70-200 as both are relatively close focusing; which means, very roughly, equivalent to somewhere around 100 mm at 12 ins which is an average distance before the subject flies away.
But for serious macro work I use a 'proper' macro lens (180 mm). One advantage of a 'macro lens' is that it should also work fine as a standard 'prime' lens.
Originally, I started getting serious about insects with a 70-300 lens plus an extension tube. These allow you to get a little closer to the subject without any loss of quality.
Then comes the need for a good tripod and possibly a flash unit; plus quite a bit of time spent learning macro photography technique.
And in my case, quite a few rather expensive identification books to work out exactly what species my subjects are.