Monarch Butterflies polulation explosion

In the middle of August every year, monarchs in the eastern North America begin to pack up and head south for the winter.
Eventually they arrive in mexico in such numbers that they turn the trees and hillsides orange.


Caterpillars turn into butterflies quicker in warm weather, and the result is an extra generation of monarchs.
It is impossible to estimate numbers since there are so many.

Where silk comes from

Silk comes from the silkworms, whose diets consist mainly of the leaves of the mulberry tree. In an effort to establish a thriving silk industry in England, James I issued an edict in 1608 encouraging the planting of the mulberry trees throughout the country. The venture proved unsuccessful, it is thought, because it was the black mulberry and not the whilte mulberry tree,eaten by the silkworms, that was planted. The white mulberry, it later turned out, struggled in England's damper climate.