ABOUT BOM SPECIES LIST BUTTERFLY HISTORY PIONEER LEPIDOPTERISTS METHODS
The Butterflies of Massachusetts
104 Dion Skipper Euphyes dion (W. H. Edwards, 1879)
Named for a somewhat elusive Greek goddess, Dione, the Dion Skipper has been appropriately elusive in Massachusetts. It is still quite a surprise when this wide-ranging species turns up. It apparently prefers calcareous or at least non-acidic wetlands north of about New Jersey, and therefore suitable wetland habitat is found almost solely in the western part of our state. The Dion has recently been found in more locations in western Massachusetts than previously thought, and may be extending its range, arriving from either Connecticut or New York or both.
Photo: Hinsdale, Mass., B Higgins, July 18, 2009
Scudder did not include this species in his magnum opus on New England butterflies. Dion Skipper either did not occur in Massachusetts in 1900, or, more likely, was so uncommon that it had not been found. Scudder conflated Dion with the Palatka Skipper. He knew of “palatka” specimens from the midwest and Florida, but none from New England. It was W. H. Edwards who first described and named Dion Skipper from an Indiana specimen (Miller and Brown 1981). Some authors recognize today’s southern populations as a separate sub-species E. dion alabamae (e.g. NatureServe 2011).
Dion Skipper has a curious distribution. It is absent from the whole southeast Appalachian Mountains area, but found along the Atlantic coastal plain from Florida north to Long Island, and then north through western Connecticut, western Massachusetts, Vermont and Quebec. From Quebec it is found in southern Canada west to the Great Lakes area and upper midwest, and then south down the Mississippi River valley to the gulf states (Opler and Krizek 1984; Layberry 1998). Lepidopterist Arthur Shapiro traces this odd biogeography to the pattern of postglacial recolonization.
According to Shapiro, Dion Skipper is one of several sedge-feeding, marsh-dwelling skippers which probably re-colonized southern New England (at least north to Connecticut, in this case) after the glacial era by moving north along the Atlantic coastal plain. Along with the Black Dash, Mulberry Wing, Two-spotted, and Broad-winged Skippers, the Dion may have migrated across New York to re-enter the Great Lakes areas from the east; --but Dion Skipper probably also reached the Great Lakes by migrating north along the Mississippi River.
Shapiro reports a noticeable “disjunct” in New York between the Atlantic coastal plain populations of these skippers and the Great Lakes populations, which he attributes to the subsequent drying up of intervening marshes (Shapiro 1970b, incl. maps). Dion Skipper today is found mostly in southwestern New York on the one hand, and Long Island on the other (Opler and Krizek 1984; Shapiro 1974). The Dion Skippers being found today in Massachusetts may have migrated north from western Connecticut, and may be from the coastal plain subpopulation rather than the Great Lakes population.
The earliest Massachusetts record, according to Dr. Dale Schweitzer’s Atlas account, is from 22 July, 1962, near South Egremont (Berkshire County); G. Taylor’s specimen in now in the Yale University Collection. There are two records from the Atlas period: 11 July 1986, Hancock (Berkshire Co.), by R. Wendell, and 17 July 1986, Stockbridge (Berkshire Co) by D. Schweitzer. Schweitzer complained in the 1980’s that western Massachusetts calcareous fens were “depauperate” in expected lepidoptera (probably mainly moths), whether from gypsy moth spraying or other causes. But he pointed out that because the Dion Skipper is a strong flier which can occupy a variety of wetland types, it was a good colonizer and might soon be expected to reappear. Overall, the low numbers of Dion Skipper in our state have resulted in its being listed as Threatened under the Massachusetts Endangered Species Act.
Host Plants and Habitat
The 1990-95 Connecticut Atlas found Dion Skipper using Carex lacustris in the wild, but also raised it on Yellow Nut Sedge (Cyperus esculentus) in the lab (O’Donnell et al. 2007). In New York its host plant is also Carex lacustris (Shapiro 1974), and this may be its only host plant in Massachusetts. Elsewhere it also uses Carex hyalinolepis and Scirpus cyperinus, and may possibly use Carex stricta (Scott 1986; Layberry 1998).
The known habitat in Massachusetts is sedge meadows, including calcareous fens, riparian marshes, stream corridors, and wet meadows (NHESP, 2/2010) . It was first found in a high quality fen in Massachusetts. Adults nectar in upland fields near the wetland.
Some authors suggest that there are habitat differences between northern and southern populations of Dion Skipper, and that the southern populations make use of a greater variety of non-calcareous and disturbed wetlands (e.g. roadside ditches) and are less associated with Carex lacustris (NatureServe 2011; Glassberg 1993).
Throughout its large but unusual range, Dion Skipper apparently exists only in scattered colonies with low population densities. In Massachusetts, the skipper could be much less common than is its habitat. Habitats can be small (a few hectares, at least for southern populations), and populations often appear small (20 or less) (NatureServe 2011).
Relative Abundance Today
After the Atlas period, Prof. Dave Wagner found a large number of Dion Skippers in Sheffield: 20+, July 1993, and 30+ at the same location in July 1994 (MBC records). Alerted by these reports, and with the beginning of annual NABA butterfly counts in 1994, MBC members have been logging more and more sightings of Dions, although not necessarily increasing numbers. Chart 104 includes the early 1990’s reports and subsequent MBC records through 2009.
Dion Skipper has been reported in 14 of the 18 years 1992-2009 (Chart 104). In 2010 a single Dion was reported from the Central Berkshire NABA Count, bringing the total of years seen to 15 out of 19 years. This sighting frequency is similar to that for some of our late-season southern immigrants, such as Ocola Skipper or Fiery Skipper.
Chart 104: MBC Sightings, 1992-2009
The Atlas found Dion Skipper to be Rare, and found in only two Atlas blocs in 1986. MBC records 2000-2007 also rank it as Rare, but now we know that it is or has become a little less rare (Table 5).
State Distribution and Locations
Map 104: MBC and NHESP Records by Town, 1985-2010
Dion Skipper has been found in 12 towns as of 2011; ten are shown in Map 104; Williamsburg and Cummington should be added as of 2010. The number of locations where the Dion Skipper has been found has increased since 1990, and its range may be increasing.
MBC records show sighting reports from six towns: North Adams, Savoy, Richmond, Hinsdale, Sheffield, Northampton (Florence), Williamsburg and Cummington. The finding of a colony in North Adams was significant, because it marks the northernmost extension of the Dion Skipper in this state. The first report from this area, which is actually a large wetland over a mile in extent, and not yet fully explored, was during the Northern Berkshire count in 1996. The known site has since been visited by a number of butterfly observers; Tom Murray’s photos, which appear at www.massbutterflies.org , were taken there in 2004. For 2003 and 2004 photos from Sheffield by Mike Nelson, see NHESP Fact Sheet (2/2010), and for 2009 photos from Hinsdale by Betsy Higgins, see above and Massachusetts Butterflies 33, Fall 2009.
The Massachusetts Natural Heritage and Endangered Species Program in 2008 and 2009 confirmed or re-confirmed sightings in four additional towns, Egremont, Stockbridge, Pittsfield, and a new site in Lee. These sightings were made by Tom Lautzenheiser of MassAudubon, and they bring the total of towns to ten. The Atlas report from R. Wendell, Hancock, 7/11/1986, should probably also be added to the map, and it would bring the town total to eleven.
Dion Skipper might be moving east within Massachusetts. A 2009 report from K. Gardner with photos of at least two, and probably more, Dion Skippers at a lakeside location in Florence, was the first record for Hampshire County, and the easternmost location so far. Dion's presence at this site was re-confirmed in 2012. Recent MBC reports from Williamsburg and Cummington spatially link the Berkshire County sightings to the Hampshire County sightings.
Opler and Krizek’s 1984 range map, like the MAS 1990’s Atlas map, showed Dion Skipper only in southwestern Massachusetts; both these maps are now out of date. Cech’s 2005 range map includes all of western Massachusetts, and shows a few reports from Vermont. In the 2002-2006 Vermont Butterfly Survey, Dion Skipper was found in 8 atlas blocs, with a total of 20 sight, photo or specimen records. Dion Skipper occurs as far north as Burlington area and Grand Isle in Lake Champlain (VBS 2010). It has also been known since 1991 north of Vermont in Canada in Quebec in the St. Lawrence valley (Layberry 1998). Whether it also inhabited these northern areas a century ago is uncertain, although there are museum specimens from Grand Isle, Vermont.
Broods and Flight Time
The Dion Skipper is univoltine at this latitude, with its concentrated annual flight in Massachusetts usually occurring from the first through the third weeks in July (http://www.naba.org/chapters/nabambc/flight-dates-chart.asp). For this reason it has been found on the Southern, Central, and Northern Berkshire NABA Counts; many of the locations so far reported are within designated count circles.
All sightings of Dion Skipper in Massachusetts have been in July or late June. Between 1992 and 2012, the earliest four records are 6/27/2010 Williamsburg Graves Farm, B. Benner; 6/30/2012 Northampton Fitzgerald Lake, T. Gagnon; 7/4/2005, North Adams, R. and S. Cloutier; and 7/5/1995 Richmond, T. Gagnon.
Between 1992 and 2011, the three latest sightings are 7/26/1997, 2, Central Berkshire NABA Count, T. Tyning et al. 7/23/2000, 3, Central Berkshire NABA Count; and 7/22/2007, 1, North Adams, R. Hamburger.
Shapiro (1974) gives the flight period in the New York Finger Lakes region as July 1- August 4, and all 1990-95 Connecticut Atlas sightings and specimens are from July or the first week of August (O’Donnell et al. 2007). The Massachusetts sightings are comparable these periods, and thus seem to represent over-wintering colonies or individuals rather than long-distance dispersals.
Outlook
Dion Skipper is not a recent and seasonal southern immigrant, like Ocola or Fiery Skippers, but rather a fairly rare marsh skipper which might have been here unnoticed since postglacial times. In habitat it is similar to Two-spotted Skipper, Black Dash and Mulberry Wing, but unlike these species it does have a midwestern and southeastern coastal range.
In Massachusetts Dion Skipper may be threatened by habitat loss and hydrologic alteration that disrupts the flooding regime in its habitat. Common reed (Phragmites australis) and other invasive wetland plants may degrade and destroy habitat. Other potential threats include introduced generalist parasitoids and insecticide spraying (NHESP 2/2010). Dion Skipper is a Threatened species in Massachusetts, and sightings should be reported at http://www.mass.gov/dfwele/dfw/nhesp/species_info/pdf/electronic_animal_form.pdf .
While habitat conservation is important, it does not guarantee the presence of the skipper. Dion Skipper may be less common than its habitat in Massachusetts, and if so conservation efforts need to be focused on existing populations of the butterfly itself, rather than solely on conserving likely habitat. More searches should be made of known habitat (e.g. North Adams), and known butterfly populations should be monitored yearly.
© Sharon Stichter 2011
page updated 7-3-2012
ABOUT BOM SPECIES LIST BUTTERFLY HISTORY PIONEER LEPIDOPTERISTS METHODS