Critters in your autumn leaves

Luna moths, beautiful and characteristic with unique wings, overwinter in cocoons which are buried in the ground. The autumn leaf litter disguises their presence to keep them safe until they can emerge in the spring. (Geoff Gallice/Wikimedia Creative Commons)

As we enter October, the cool nip in the morning and slowly rusting trees remind us of our transition into autumn. In just a few weeks, we will be enjoying crunchy leaves on the sidewalks while homeowners collect those that litter their yard and get rid of them elsewhere. However, there may be more lurking in a pile of dead leaves than you might imagine.

They’re small, they don’t have a spine, and they make up the vast majority of animal species on the planet. Many invertebrates, such as insects, snails and worms, love to nest in and feed on leaf litter, including the fallen leaves we see all over New England in autumn.

In nonresidential areas such as forests, fallen leaves build up on the forest floor, slowly decay and provide the ecosystem with loads of nutrients which cycles through the seasons. This provides the areas with not only natural fertilization to help feed the trees, but it also acts as an important overwintering habitat for many tiny and beautiful animals.

Everyone will notice that in the summer, insects and other invertebrates thrive and are in high abundance. Moths flood at your lights at night, mosquitos are rampant and even spiders are much more active. However once the winter months approach, they need to find a way to survive the freezing temperatures until the next season. To do this, many species overwinter, or they find a place to hunker down to keep them warm enough until they can emerge the next year. Autumn leaf piles are prime candidates for a diverse group of invertebrates.

Luna moths, beautiful and characteristic with unique wings, overwinter in cocoons which are buried in the ground. The autumn leaf litter disguises their presence to keep them safe until they can emerge in the spring.  According to folklore, the proportion of the black and brown fluff covering wooly bear caterpillars determines the severity of winter to come. They are also on the search for leaf piles to keep them warm throughout the winter, so they can emerge as yellow tiger moths in the spring.

The earthworms, millipedes and snails that live in these leaf piles will chew on the debris to create smaller pieces, providing food sources for other invertebrates such as springtails or mites. These smaller pieces will eventually be decomposed by even tinier forms of life like fungi and bacteria, returning nutrients into the soil. These leaf piles don’t only contain herbivores to eat the leaves; predators such as beetles, spiders and centipedes will move through the piles and eat a variety of the small invertebrates to keep the populations in check.

Although invertebrates get a bad rep from the public of being creepy crawly critters, they provide a massive amount of ecological importance to both wild forests and residential yards. A yard that supports the urban diversity of these population will be much healthier, and will attract many more charismatic animals such as butterflies and birds. So next time you go out to rake up all the dead leaves on your yard, think again about whether you want to throw out these communities or let your yard flourish with biodiversity opportunities.


Sarah Hurley is a campus correspondent for The Daily Campus. She can be reached via email at sarah.hurley@uconn.edu.