(Chelsea Update would like to thank Tom Hodgson and the Waterloo Natural History Association for the information and the photos in this story.)
Wetlands produce more biomass (weight of plants and animals) per acre than any other habitat including tropical rain forests.
And, the Chelsea area is blessed with an abundance of wetlands on both public and private lands. Unfortunately because they are wet, they are not particularly visitor friendly most of the year. But, the winter season is the one exception. Wetlands are usually frozen solid by January and readily available for exploration until the spring thaw.
One of the easiest to wetlands to explore is the buttonbush swamp. There are many small, shallow, seasonal ponds and swales that support wetland shrubs including buttonbush.
Buttonbush gets its name from the round seed heads that adorn its bare, winter branches. They not only make buttonbush easy to recognize, but also are an important natural food source for winter birds.
During the summer, buttonbush leaves are a preferred food source for the caterpillars of two species of giant silk moth, the cecropia and promethea. By the end of the summer, these caterpillars have hidden themselves in silken cocoons that remain attached to the branches of their host until the following June. During the winter season, with careful observation, one can find these cocoons hidden among the leafless branches.
The cecropia cocoon looks like a small brown, silken bag adorned with dried, brown leaves.
The promethean cocoon is smaller and usually wrapped in a single leaf. Inside of each cocoon is a single pupa, looking a lot like a little, brown mummy; that will remain dormant until June when the beautiful adult moth will emerge.
Adult silk moths are non-feeding, living just long enough to mate and lay eggs. The cecropia is Michigan’s largest moth with a wingspan of about six inches, while the promethea is slightly smaller, but no less beautiful.
The promethean flies in late afternoon and evening, while the cecropia is strictly nocturnal.