Oarisma poweshiek

The Poweshiek skipper is a prairie obligate butterfly--it needs high quality prairie to survive. If you read the butterfly guide books, the caterpillar host plant is identified as spike rush--Eleocharis elliptica. Although several guide books repeat this information, there has been some analysis, summed up by Selby, 2006 (see the US FWS link below) that casts a lot of doubt on that idea.

Oarisma poweshiek is rare where ever it is found. It is not listed as an endangered species federally, but it is on several local threatened and endangered lists. The table below shows the status:

Until recently this butterfly was assumed to be rare but to be found in about 25-30 relatively stable populations in Iowa. Butterfly experts in Iowa started coming back from prairies with anecdotal evidence that the butterfly had vanished from some of the prairies with known large populations in about 2003. Extensive surveys for O. poweshiek in 2007 found the butterfly at only 2 sites in Iowa. Therefore, the status of the butterfly may need to be re-evaluated.

Special thanks to Frank Olsen for the photograph on the right of O. poweshiek. This is one of the four individuals of the species that was seen in the state of Iowa during the year 2007.

UPDATE: In spite of a large number of observers looking for the species in 2009, no individuals were seen in Iowa, Minnesota, or South Dakota. 2009 was a bad year for butterflies in general, but this is not good news.

Threatened and Endangered Status of the Poweshiek skipper

State or Country	Status
USA	Not listed (federal list)
Canada	Listed under Canada’s Species at Risk Act (SARA)
Iowa	Threatened
Minnesota	Special Concern
Wisconsin	Endangered
North Dakota	North Dakota has no state T & E list
South Dakota	Not listed (very small list)
Michigan	Threatened
Illinois	Not listed
Indiana	Not listed (no insects on T & E list)
Other: Xerces Society Red List of Pollinator Insects of North America	Imperiled See link below:
Nature Serve	G2:::”global imperiled”

There are a number of reports about this species available on the internet. The Selby report listed above can be found at:

http://www.fws.gov/midwest////Endangered/insects/posk_sa.html

A Wisconsin DNR information page about the species can be found here:

http://dnr.wi.gov/ORG/LAND/ER/invertebrates/butterflies_moths/pskipperling.htm

Information from Canada can be found here:

http://www.cbif.gc.ca/spp_pages/butterflies/species/PoweshiekSkipperling_e.php

Good photographs can be found on this Michigan site:

http://web4.msue.msu.edu/mnfi/explorer/species.cfm?id=11594

The Xerces Society has an information page here:

http://www.xerces.org/wp-content/uploads/2008/09/oarisma_poweshiek.pdf

Here is a Minnesota DNR page courtesy Robert Dana:

http://www.dnr.state.mn.us/rsg/profile.html?action=elementDetail&selectedElement=IILEP57010

Even though most of this information is fairly recent, it is also dated--the drastic decline in Iowa and parts of Minnesota is not mentioned in these reports.