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Thursday, November 11, 2021

Leave the Leaves!

Fallen leaves are not 'litter', but are food and shelter for many forms of wildlife.

This time of year, as the days shorten and leaves begin to fall, we can’t seem to help wanting to tidy up our yards and gardens by constantly mowing, blowing, and edging.  However, one of the most valuable things you can do to support pollinators and other beneficial species is to provide them with winter cover in the form of fallen leaves and dead plant material.

The Texas Alligator Lizard breeds in October or November, with females delaying egg
development during hibernation, laying their eggs in leaf litter beginning in February.

Leaves on the ground are not litter, which is unfortunately how most people see them.  Rather, they are food and shelter for many species of bees, beetles, butterflies, moths and other native creatures.  They are also habitat for beneficial snails, spiders, worms, millipedes, mites, and other small species that support the larger species such as birds and mammals that use them for food.

The larva or caterpillar of the Dusky-blue Groundstreak butterfly feeds on decaying leaves.

The vast majority of butterfly and moth species overwinter in the form of an egg, caterpillar, chrysalis, cocoon, or adult.  Some tuck themselves into a pile of leaves for protection from predators or the cold.  Others lay their eggs on fallen oak leaves, which becomes their first meal when they hatch in the spring.  Cocoons and chrysalises are often disguised with dried leaves, keeping them safe by helping to blend in and avoid predation.  Some species of lizard lay their eggs in fallen leaves, and many species of native bees and Sphinx moth larvae burrow into shallow soil for the winter, each attempting to survive the colder months covered in a protective blanket of leaves. 

The pupa (or immature inactive form between larva and adult)
of several species of Sphinx Moths, like this Virginia Creeper Sphinx,  
spend the winter a few inches under the soil, protected by a blanket of leaves. 

So how do you maintain your property while leaving the leaves?  First, if you must keep your lawn free of leaves, use a manual rake (it’s good exercise, too) and make a leaf pile in a corner of your yard or pile them up around your trees, shrubs, and perennials.  Don’t shred the leaves but keep them whole, let the leaf pile break down naturally, and leave the leaves that have already fallen in your beds and yard edges.  This free mulch provides you with valuable organic matter, builds up healthy soil, insulates tender roots, retains moisture, and helps to keep weeds at bay.   You can always decide to remove the leaves in the spring, once you wait late enough in the season so as not to destroy any overwintering species.

An adult Snowberry Clearwing Moth emerges from the leaf-covered ground in spring. 

And if the human side of things is more of a motivator for you, consider that the U.S. Environmental Agency has reported that mowers, edgers, and blowers used to remove leaves emit 27 million tons of air pollutants each year, not to mention the noise pollution that they create.  So do consider leaving the leaves this year, it’ll be less work for you and much better for the wildlife!

The Xerces Society encourages everyone to 
Leave the Leaves!