In western Washington, the 20th century was tough on prairies. Most open acres were farmed or developed into oblivion. As wildfires were extinguished and native prairie-burning ceased, both forests and plagues like the introduced Scot’s Broom and invasive grasses took over, smothering the native prairie habitats. Not surprisingly it was a rough century for prairie butterflies too.

Four butterflies, especially, have suffered the brunt of prairies loss here in the Puget Trough: the Puget Blue (Icaricia icariodes blackmorei), the Valley Silverspot (Speyeria zerene bremnerii), the Mardon Skipper (Polites mardon), and the Taylor’s (or Whulge) Checkerspot (Euphydryas editha taylori). [Whulge, as The Butterflies of Cascadia will tell you, is the native (Salish) name for the Salish Lowlands = Puget Trough].

Earlier this month I sat down with Dan Grosboll (Fort Lewis Project Manager for The Nature Conservancy and recent butterfly biologist with the WA Dept. of Fish and Wildlife) to discuss Taylor’s Checkerspot. Dan has developed rearing techniques for raising this butterfly, studied it in the field and worked to improve habitats where E. e. taylori once flourished, so he has a broad and unique perspective on this imperiled critter. Here is some of what I learned from him.

Once common, even abundant, in places like the 13th Division Prairie at Fort Lewis, Glacial Heritage Preserve and Mima Mounds as recently as the early 1990s – the last South Sound populations are now limited to the Bald Hills Area in southwestern Thurston County and the Artillery Impact Area at Fort Lewis south of Tacoma. There are also a few populations near Port Angeles and in Oregon’s Willamette Valley. All of these populations are small, unstable and vulnerable; and several organizations, including the Xerces Society, have sued the US Fish and Wildlife Service to list E. e. taylori as endangered before it disappears forever.

Although native larval food plants including Harsh Paintbrush (Castilleja hispida) and Small-flowered Blue- eyed Mary (Collinsia parviflora) have been recognized for a long time, a new host plant has recently been identified in South Sound study areas: Sea Blush (Plectritis congesta).

One of the most common host plants for this lowland subspecies of Edith’s Checkerspot has been the introduced English Plantain (Plantago lanceolata). This plantain, unlike many native hosts that senesce early in the year, remains green well into summer. This is may be important, as Dan points out, because the main cause of

E. editha mortality is pre-diapause larval starvation and he speculates that the extra food may lead to a boom and bust cycle that makes populations  more  vulnerable  to extirpation.

Larvae enter diapause after the 4th instar (mid-June to early July) and emerge as early as the following February to continue their growth. One of Dan’s most interesting findings is that these spring-time larvae bask on open and mossy south-facing slopes at Bald Hill Natural Area Preserve. [Butterflies bask, so I suppose it should be no surprise that caterpillars do too.] These basking sites include the main access trail, so DNR is likely to restrict access between February and April.

Dan says that, when restoring prairies, The Nature Conservancy (TNC), “tries to see things through the butterfly’s lens.” For example, when working around host plants, volunteers pull Scot’s Broom by hand to protect the native plants. Broom is being removed from a number of promising balds adjacent to Bald Hill NAP. TNC staff and volunteers have also been re-establishing habitat by planting native host plants: paintbrush for Checkerspots, Viola adunca for Valley Silverspots, and Roemer’s Fescue (a subspecies or variety of Idaho Fescue) for Mardon Skippers. The restorative use of fire, and eliminating Scot’s Broom and invasive grasses also are critical.

Much of this work has been supported by partners – Dan credits the funding and assistance from Fort Lewis for restoration work, while the captive rearing was supported by the Washington Department of Fish and Wildlife. WBA volunteers, organized by Bob Hardwick, assisted by conducting butterfly surveys on the prairies of Fort Lewis; and Dave Nunnallee raised Mardon Skipper larvae.

Because Taylor’s Checkerspot populations have “winked out” at many sites, reintroduction is a long- term goal. Dan has passed the captive-rearing torch to researchers at the Oregon Zoo in Portland who will be working to increase production of adults. Timing adult emergence remains one of the main challenges, as captive butterflies miss the development cues that they would get in nature. If good numbers of this handsome butterfly can be raised to emerge in synchrony with prairie host plants, and if prairie habitats can be protected and restored to meet the butterfly’s needs, there’s a chance E. e. taylori may make it though the 21st Century.

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