Moths, Caterpillars, and Restoration of Remnants 

By Robert J. Marquis

October 1, 2023

Schinia lucens adult on leadplant, Blueberry Hill Prairie, photograph by Christopher Smith. 

The goal of The Prairie Enthusiasts is to preserve and restore prairies and savannas in the Upper Midwest.  By this we mean the protection of the entire ecosystem, not only the plants but also the animals and microbes and all their intricate interactions with those plants and each other. It has long been feared that conservation efforts might result in “empty forests” (or in our case, “empty prairies”) in which the landscape appears to be intact but close-up, many if not all the once known animal inhabitants are missing. A major challenge is to document the effects of prairie and savanna management on the animal participants and their place in prairie food webs.  

 

The St. Croix Valley chapter in conjunction with Minnesota Department of Transportation (MNDOT) has managed a small remnant prairie (15 acres) for 18 years. This prairie, known as the Blueberry Hill Prairie, lies on the western bluff  (Minnesota side) of the St. Croix River, just opposite Hudson, Wisconsin. Beginning in 2013, volunteers of the chapter began to convert 11 acres of adjacent agricultural land into prairie. In 2023, the chapter initiated efforts to document the interactions between insects and plants that occur in the Blueberry Hill Prairie.  

One particular interaction of interest is that between leadplant (Amorpha canescens (Fabaceae)) and the Leadplant Flower Moth (Schinia lucens (Noctuidae)) (Swengel and Swengel 2006). The Leadplant Flower Moth occurs from western Michigan to eastern Montana, south to Illinois, Iowa, Nebraska, and Oklahoma, and then again in Florida and South Carolina in the East, and in California and Arizona in the West (http://mothphotographersgroup.msstate.edu/species.php?hodges=11174). On July 6, 2023, Christopher Smith of MNDOT and Wayne Huhnke, a member of The Prairie Enthusiasts and steward of Blueberry Hill Prairie, searched the local population of leadplant on the prairie remnant for the Leadplant Flower Moth. After searching some over 500 plants, they found a single moth, which they photographed (Fig. 1). Surveys of lead plant at the Rocky Branch Prairie and the Foster Cemetery Conservation Area, both in the City of River Falls, Wisconsin, revealed no adults this year. The moth is bright mottled pink (Hess and Hatfield 2015, Henderson 2017), and therefore not easily missed.  

Black light setup before sunset (left) and after in the dark (right). Photographs by R. Marquis

The Leadplant Flower Moth is endangered in Michigan (Michigan DNR 2023) and Indiana (Indiana DNR 2023), of special concern in Minnesota (Minnesota DNR 2023), and of greatest conservation need in Wisconsin (Wisconsin DNR 2023a). It is highly specialized in habitat, food plant, and phenology, and it is this combination of characteristics that makes it vulnerable. In the Upper Midwest, it is found only on prairie, caterpillars feed only on leadplant, and then only on the flowers and developing fruits of the plant. This lifestyle forces it into a very narrow time window of activity. In the Upper Midwest, we might suspect that caterpillars of this species could also survive and mature on fruits of Amorpha fruticosa (indigo bush), given that even highly specialized species often can feed on more than one member of the same plant genus. But there are no feeding records for A. fruticosa (Robinson et al. 2002), perhaps because that plant in Wisconsin and Minnesota grows in moist woodlands, along streams, and in floodplains. The moth does occur outside of the range of A. canescens, meaning that it must feed on additional host plant species.  

Late instar caterpillar of Schinia lucens, collected on leadplant at Blueberry Hill Prairie. Photo by R. Marquis
After finding the moth adult, the chapter held its first black-lighting event at Blueberry Hill Prairie on July 25, 2023 (Fig. 2). One goal was to attract more adults of this species to get a better sense of the population size. Schinia lucens adults are attracted to ultraviolet lights, establishing that they do fly at night (The Lepidopterist’s Society 1983, 1984). The other goal of black lighting was to more broadly survey the moth species that occur at that prairie. No Leadplant Flower Moths came to the lights that night, perhaps because it was past the flying date of adults. Using a beating sheet placed under lead plants, however, and gently shaking the plants, we were able to find two caterpillars suspected to be of the species. We reared one to a late instar, photographed it (Fig. 3), and then returned it to Blueberry Hill Prairie. The photos match those published online (identification by J. Sorgaard, pers. comm.). The caterpillar ate only developing fruits even though stems and leaves of leadplant were made available. At this time, seven other species of Lepidoptera are known to feed on leadplant parts (Hess and Hatfield 2015, R. Henderson, pers. comm.). None of them are sufficiently similar enough to confuse them with members of the genus Schinia.  
Given the decimation of North American prairie, it is not surprising to learn that five of seven species of Lepidoptera (moths and butterflies) listed as endangered or threatened in Wisconsin are prairie and savanna species (Wisconsin DRN 2023b), and all nine endangered or threatened Lepidoptera species in Minnesota are of prairie or savanna (Minnesota DNR 2023). A twelve-year survey of prairie and savanna sites in the Chicago area never or rarely encountered 44% of the insect species that are considered prairie/savanna specialists for the region (Panzer et al. 2010). All is not without hope, however. Even small prairie remnants, if of high quality, are not “empty,” as they can harbor prairie specialists (Panzer et al. 2010). In addition, restoration of prairie can be effective in augmenting species diversity and abundance. In Iowa, restored prairie begins to approach remnant prairies in moth diversity after seven years (Summerville et al. 2007). Restoration of prairie in Wisconsin, resulting in increased abundance of leadplant and the leadplant flower moth, further suggests that management can be an effective tool to recovering interactions (Henderson 2017). We will continue to monitor the status of Schinia lucens at Blueberry Hill Prairie, and at the other sites managed by the St. Croix Valley Chapter.  

Citations 

Henderson, R. 2017. Of checks, balances & seed production. The Prairie Promoter 30:6,8. 

Hess, M., and M.J. Hatfield. 2015. One plant at a time. The Prairie Promoter 28:1,4. 

Indiana DNR. 2023. Indiana county endangered, threatened and rare species list. https://www.in.gov/dnr/nature-preserves/files/np-Indiana-County-Endangered-Threatened-Rare-Species-List.pdf. Accessed 30 August 2023.  

Michigan DNR. 2023. Threatened and endangered species list. https://www.michigan.gov/dnr/managing-resources/wildlife/wildlife-permits/threatened-endangered-species/threatened-and-endangered-species-list. Accessed 30 August 2023.  

Minnesota DNR. 2023. Minnesota’s endangered, threatened, and special concern species. https://www.dnr.state.mn.us/ets/index.html. Accessed 31 August 2023. 

Robinson G.S., Ackery P.R., Kitching I.J., Beccaloni G.W., Hernández L.M. 2002.  

Hostplants of the moth and butterfly caterpillars of America north of Mexico. Memoirs of the American Entomological Institute, v. 69, 824 p. 

Summerville, K.S., Bonte, A.C. and Fox, L.C., 2007. Short‐term temporal effects on community structure of lepidoptera in restored and remnant tallgrass prairies. Restoration Ecology, 15(2), pp.179-188. 

Swengel, A.B. and Swengel, S.R., 2006. Variation in detecting Schinia indiana and Schinia lucens (Lepidoptera: Noctuidae) in Wisconsin. The Great Lakes Entomologist, 39(3 & 4), p.6. 

The Lepidopterists’ Society. 1983. Season summary. News Lepidoptera Society, no. 2. 

The Lepidopterists’ Society. 1984. Season summary. News Lepidoptera Society, no. 2. 

Wisconsin DNR. 2023a. Species of great conservation need. Wisconsin wildlife action plan. https://dnr.wisconsin.gov/topic/WildlifeHabitat/actionPlanSGCN. Accessed 30 August 2023.  

Wisconsin DNR. 2023b. Wisconsin’s endangered and threatened species list. https://dnr.wisconsin.gov/topic/EndangeredResources/ETList . Accessed 30 August 2023.  

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