Rare Species Guide

  Basis for Listing

Modern records of Phlox Flower Moth (Schinia indiana) occurrence are limited to four upper Midwest states: Minnesota, Wisconsin, Indiana, and Michigan. There are also historical records from Illinois, Arkansas, and Texas. There are only about a dozen recently documented sites throughout its range, seven of these in Minnesota.

Although the Phlox Flower Moth was undoubtedly a common species in Minnesota prior to Euro-American settlement, the first records of its occurrence in the state are 1976 and 1978 collections. These were made during a survey of pollinators in a prairie preserve, but their identity was not recognized until 1981. The next site was added in the mid-1990s, and four more were discovered in 2006 and 2007. The discovery of the seventh site occurred in 2014. These seven sites are native prairie remnants, distributed among as many counties, all in the region of the state originally dominated by prairie (North-Central Glaciated Plains Section). In this part of the state, the larval moth’s exclusive food plant is rarely found outside of remnant prairie habitat, which comprises only a little more than one per cent of its former expanse in the state (Minnesota’s Remaining Native Prairie). The adults are difficult to detect (Swengel and Swengel 2006), and targeted surveys for this species in Minnesota did not begin until 2006. Phlox is also present in sand prairie, savanna, and barrens habitats east of the prairie region in Minnesota, but no survey has yet targeted these. Balancing the limited amount of survey effort directed to it in Minnesota with the possible global rarity of this species and its dependence on much diminished and vulnerable habitat, in 1996, the state listed the Phlox Flower Moth as a species of special concern.

  Description

The Phlox Flower Moth is a small compactly-built species. Its wingspan is 15.5-18.0 mm (0.6-0.7 in.); however this will rarely be observable in living moths. At rest, with its wings folded back over its abdomen in tent-like fashion, it measures front to back about 9mm (0.35 in.); and across the widest part of the folded wings, about 5mm (0.20 in.). Males and females are similar in size and coloring. The upper side of the forewing is crimson, typically with slightly lighter frosted-looking basal, median, and terminal bands alternating with antemedian and subterminal bands of darker, purer color. This patterning is subtle and sometimes imperceptible. In fresh individuals, there is a pale tan or whitish-gray fringe. The resting moth matches the color of a freshly wilted phlox corolla. The upper side of the hindwing, not visible in the resting moth, is uniformly black, bordered with a whitish fringe. Head and thorax are densely clothed in gray hair. Antennae are threadlike in both sexes.

The Phlox Flower Moth is not likely to be confused with any other moth species in Minnesota. The related Bleeding Flower Moth (Schinia sanguinea) may sometimes be close in coloring, but typically the pink to crimson color of the forewings is conspicuously patterned with white to tan markings. It is also twice the size of the Phlox Flower Moth, and the adult flight period is in late summer when its larval hosts, blazing stars (Liatris spp.), flower. Females of the Wedgeling Moth (Galgula partita) are close in size and wing coloring and can be present during the Phlox Flower Moth’s flight period, but the color of its forewings is browner, and the hair scales clothing the dorsal thorax are the same dark color as the wings, not gray.

  Habitat

All documented occurrences in Minnesota are in native upland prairie, ranging from wet-mesic to dry-mesic. In all cases, prairie phlox (Phlox pilosa) is common. East of Minnesota, typical habitats are reported to be native plant communities on sandy soils, including open woodland, savanna, and barrens (NatureServe 2020). This may reflect the fact that these agriculturally inferior soils are the only significant areas left in this part of its range with native plant communities in which prairie phlox is common.

  Biology / Life History

Phlox Flower Moth adults emerge from their pupal stage beginning in mid-June; they mate and lay eggs during a roughly three-week period, and have all completed their life by early July. This is fairly synchronous with the flowering period of prairie phlox. This plant is the only documented larval host for the Phlox Flower Moth. Females lay eggs singly, typically attached to flower calyces; by the time of hatching, the corolla has withered and dropped off, leaving the attached egg in close proximity to the developing seed pod. The earliest larval stages bore into the pods and feed internally on the seeds, then later stages, too large to fit inside the pods, cut a round hole in the capsule wall large enough for their head to reach the seeds. Late-stage larvae are green with a dark purple mid-dorsal stripe. When their growth is complete, larvae burrow into the soil to pupate, apparently deeply enough to be protected from prairie fires (NatureServe 2020). Pupation occurs promptly after completion of the subterranean cell, and winter is passed in pupal diapause. Emergence of adults in June completes the one-year generational cycle. Some pupae may await another year to emerge; however, this has not been confirmed.

Adults are active during daylight hours; however, their small size, dark coloration, and low, rapid flight makes them hard to detect except when resting amid the flowers of phlox inflorescences; and their camouflaging coloration makes even this challenging. Under sunny, warm conditions, resting adults will flush readily, typically before being spotted; cloudy conditions provide the best chances of success. Adults are not attracted to lights at night, indicating that they are not nocturnally active (NatureServe 2020). The moths feed on floral nectar; phlox may be the principal source; however, observation of adults captured by crab spiders (Thomisidae) and ambush bugs (Phymatinae) on other flowers indicate some degree of wider usage (personal observation). The frequency with which mating pairs are observed on phlox inflorescences suggests that this is the common location for mating (Swengel and Swengel 2006).

  Conservation / Management

The Phlox Flower Moth’s survival in Minnesota clearly depends on the preservation of sufficient native prairie habitat with prairie phlox to support multiple populations. There is no information on the dispersal behavior of this species, nor on typical densities in such habitat; making it impossible, at this point, to model population dynamics for guidance on how many sites, of what size, and separated by what distances would be needed. This will require much fundamental research. In the meantime, additional survey is critical to clarify the actual status of the moth in the state.

Fire stimulates subsequent flowering in prairie phlox, making this an important tool for maintaining habitat quality for the moth. Fortunately, the subterranean position of the overwintering pupa and the timing of entry and exit substantially reduce its exposure to lethal temperatures during dormant-season fires, when most prescribed burning for prairie maintenance is done. However, rotational burning is still important for the moth’s persistence in a site. Burns that delay flowering enough to desynchronize the moth’s and plant’s phenologies could seriously depress the moth’s reproductive success. A burn late enough to prevent flowering for the season would likely extirpate the local population as would burns during the adult flight and larval development periods. Mowing (with removal of the cut material) is probably an effective alternative to burning in small sites where rotational burning would be difficult, but like burning, this should not be done until larvae have finished feeding and burrowed into the soil, early August at the earliest.

Prairie phlox is sensitive to grazing pressure and can be eliminated from the prairie community by season-long heavy grazing. Grazing management, even if compatible with an abundance of phlox, must avoid seasonal suppression of flowering by grazers as well as consumption and trampling of plants during fruiting.

  Conservation Efforts in Minnesota

The goal of protecting remnant prairie habitat and managing it has been the conservation of all species that are its characteristic inhabitants, including those not yet recognized as such. Before the listing of the Phlox Flower Moth as a species of special concern in Minnesota, this was really the only conservation effort that benefitted it. All but two of the sites documented to support this insect are in State Wildlife Management Areas or natural area preserves owned by The Nature Conservancy, whose protection long preceded detection of the moth’s presence. The listing of the Phlox Flower Moth in 1996 as a species of special concern (SPC) under the state’s Endangered Species Statute and its inclusion as a Species of Greatest Conservation Need (SGCN) in the Minnesota's Wildlife Action Plan in 2005, have increased awareness of the need for conservation of this species. Minnesota DNR surveys targeting the Phlox Flower Moth beginning in 2006 are a direct result. Much additional survey work is needed.

Another result of listing is that all occurrence data for this species is entered in the Natural Heritage Information System, a DNR database that the state environmental review process consults, assuring that impacts to this moth will be considered in decision-making. Managers of protected prairies will be informed of known occurrences.

  Authors/Revisions

Robert P. Dana, Ph.D., 2025

(Note: all content ©MNDNR)

  References and Additional Information

Hardwick, D. F. 1996. A monograph to the North American Heliothentinae (Lepidoptera: Noctuidae). David F. Hardwick, Ottowa, Ontario. 281 pp.

NatureServe. 2008. NatureServe Explorer: An online encyclopedia of life [web application]. Version 7.0. NatureServe, Arlington, Virginia. . Accessed 9 June 2008.

Swengel, A. B., and S. R. Swengel. 1999. Observations on Schinia indiana and Schinia lucens in the midwestern United States (Lepidoptera: Noctuidae). Holarctic Lepidoptera 6(1):11-21.

Wisconsin Department of Natural Resources [WIDNR]. 2008. Phlox Flower Moth Schinia indiana (Smith). . Accessed 28 October 2008.