The Spring has come again
For the grass is growing green,
And among the fields of clover
Bright butterflies are seen.
The little birds are singing sweetly
As they fly from tree to tree…
The busy bees are gathering
The honey from the flowers,
And the merry birds are building
Their nests in sheltered bowers…
~Josephine D.C., “Spring,” c.1887
There are less romantic ways of saying when Spring is here, a few objectively theoretical but most are practical. This one is entomological:
In the US, populations of inchworm caterpillars can eat the buds and new leaves from trees and reduce whole forests. After they have eaten all of the leaves on a tree, they use their webs to swing to the next one like tiny Tarzans. Then they drop to the ground from their threads and spin their cocoons.
In Europe, the Spring caterpillars often crawl in trains, to confuse predators.