This large butterfly is famous for its large-scale migrations into America, where it moves in groups of millions of individuals over distances of up to 4,000 km, twice a year, from August to October to the south, especially in Mexico and in spring to the north."

This is absolutely INSANE. Nature is completely wondrous on the way it creates these incredibly resilient creatures. It totally reminds of all the possibilities and unique traits each and every one of us have, doesn't it?

While researching the nivosus phenotype after you mentioned i have found the most interesting informations on the mechanism behind the pigment of the wings of a Monarch

Check it out!

Wing Pigmentation
The color of a Monarch's wings is due entirely to its wing scales. The cuticle of the wing itself is usually colorless, and the color pattern is essentially a finely tiled mosaic of monochrome scales (Nijhout 1991). Each scale gains its respective color due to the presence of various pigments found within the scale. These pigments can be categorized as melanins, ommochromes, pterins, flavonoids, and bile pigments. The most common pigments are melanins, tyrosine derivatives (Nijhout 1991), and they range in color from the typical black to yellow, brown and even red (Kayser 1985). Ommochromes are derived from tryptophan and characterized by a red-to-brown color (Nijhout 1991). Pterins are white and yellow-to-red pigments derived from guanosine triphosphate, and have yet to be found in any family except for the Pieridae (Nijhout 1991). Flavonoids are very diverse in color, and likely to be derived from food plants by the larvae and ultimately deposited in the wings of the adult. Flavonoids are thought to be limited to mainly the more primitive butterfly families (Kayser 1985). Lastly, the bile pigments (like bilins and biliverdin) are derived from glycine and are typically blue in color (Kayser 1985). Although there are numerous studies on scale pigments, the pigment-forming pathway that is being affected in the nivosus Monarch remains to be shown.

What do you think @Indesta120282 ? Isn't the absence of the various compounds that pigment the scales a good enough explanation for the white color of the nivosus phenotype? Or have i misunderstood something?

Great post, by the way!