I took an ant from my backyard and when viewed in the ESEM discovered that it was eating another bug - guess I interrupted his breakfast.
Electron images are black and white, but colors can be applied in meaningful ways, or just artistic. You can have the electronics apply a color to each channel and mix them into one image; for example, the information from one detector appears blue and the info from another appears orange, then you can visually distinguish between signal from topography and signal from average atomic number contrast (compositional variations) presented in a single image. Many SEMs are equipped with EDS and can generate compositional maps showing each element as a different color. Also, EBSD can produce color images where colors represent different crystallographic orientations.
Unfortunately, there isn't much info provided with these images so we are left to guess what the colors mean, if anything. My guess is that most (perhaps all) of these are colored for aesthetics, but there are plenty of examples of SEM images where the colors mean something. Equipment manufacturers' websites have lots of nice images also. I like FEI, which has some examples of signal mixing http://www.fei.com/resources/image-gallery/list.aspx
. Check out this critter, looks like sandworm of Dune http://www.fei.com/resources/image-gallery/hydro-worm-2908.aspx
. Oxford Instruments has examples of informational color images produced by EDS and EBSD http://www.oxford-instruments.com/products/x-ray-microanalysis/Pages/home.aspx