One of the best things you can do to support pollinators---bees, butterflies, beetles, & moths---is to let fallen leaves stay on the ground! Fallen leaves become food & shelter to insects that overwinter in our landscapes, protecting them from predators and the cold.
Although Monarch butterflies migrate, most butterflies and moths spend the winter in the landscape as an egg, caterpillar, chrysalis, or adult, & all these stages use leaf litter for winter cover. Fallen leaves may become the first food of caterpillars in the spring.
Some bees burrow into the soil to hibernate for winter; a layer of leaves helps protect them.
Fallen leaves are free mulch. They suppress weeds and retain moisture, and the decaying organic matter enriches the soil.
Go to https://xerces.org/2017/10/06/leave-the-leaves/ to learn more.