This video says about itself:
13 November 2009
A treasure trove of insect life goes about its business in leaf litter collected after mowing.
From the Cornell Lab of Ornithology in the USA:
Leaf Litter: Let It Lie
One of the great joys of fall is jumping into a huge pile of leaves—and one of the great aches and pains is bagging those leaves and throwing them out. But that doesn’t have to be—it’s often a better idea to let leaves stay on the ground.
They’ll fertilize your yard, offer snug spots for caterpillars to spend the winter, and help fill your yard with life next spring. Our YardMap project has tons of great ideas on how to make yards friendly to birds and other wildlife—read more leaf-litter tips here.