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Cofrin Center for Biodiversity

Archive for the ‘Econotes’ Category

A Returning Rabble of Admirals

Red Admiral, Photo by Ron Eichhorn

Red Admirals are one of the first butterflies seen in spring. Photo by Ron Eichhorn

This past weekend I stepped into my garden to be greeted by several red admiral (Vanessa atalanta) butterflies. According to our phenology records, the first sightings were in early April, but this year we started receiving reports of larger groups (rabbles) of admirals in late April. This is unusual for this species, which is territorial and usually found singly. It may be that warm southern winds helped to push the butterflies north.

Red admirals can only survive mild winter temperatures, so it is most likely that the butterflies we see in April are migrating from farther south. According to WI butterflies there are occasional outbreaks of large numbers of red late June and early July. The last event was in 2007. It is not known what causes these outbreaks, but we do know they are the offspring of those early migrants who laid their eggs on nettles in early May. A friend who found herself in an outbreak a few years ago at Point au Sable said there were so many that she could hear them flyinng. Perhaps this year we might be privileged to see hundreds of these beautiful butterflies this summer. They are common through northeastern Wisconsin; look for them in woodland openings and suburban areas. And let us know at our phenology pages.

You can follow the migration on University of Iowa’s <em>Vanessa Migration website. Entomologist Royce J. Bitzer has been tracking the migration of these and other butterflies since 2001. You can enter your data and follow the North American migration in google maps.

Pollen Eater

Soft-winged flower beetle feeds on pollen of Marsh Marigold.

Soft-winged flower beetle feeds on pollen of Marsh Marigold.

Marsh marigold (Caltha palustris) is a beautiful spring ephemeral flower locally common in wet forested areas.  Baird Creek in Green Bay offers spectacular views of this flower. This photo of a soft-winged flower beetle called Collops feeding on protein-rich pollen (and perhaps sugary nectar) shows that it’s not only humans that are attracted to this early bloomer. 

Pollen is an important food source for many herbivorous organisms that mainly feed on nectar or fruits that are often low in protein. In some Coleoptera pollen provides the nutrients needed to for growth and also to produce eggs.

Soft-winged flower beetles (family Melyridae) are not a particularly well-known group of beetles, despite the fact that over 500 species occur in North America.  Many feed on pollen, and although it would seem that this would be deleterious to the plant, the beetles inadvertently transfer pollen between flowers and can be effective pollinators, just like their more famous (and graceful) relatives, such as butterflies. 

Both flower and beetle are not only colorful accents in our spring landscape, but they also have roles to play in their ecosystems, and help to support other organisms and increase the biodiversity in our region.

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