ABOUT BOM SPECIES LIST BUTTERFLY HISTORY PIONEER LEPIDOPTERISTS METHODS
The Butterflies of Massachusetts
97 Little Glassywing Pompeius verna (W. H. Edwards, 1862)
The sprightly ‘little glass-wing’ has become much more common here since the 19th century. Scudder called it “exceedingly rare” in New England, and “confined to the southern portions" (1889: 1745). He does not mention it in his 1862 list of butterflies of New England, having evidently not seen any specimens by then. By 1889 he can cite specimens from only four Massachusetts locations, all in the Connecticut River valley: Mt. Tom, South Hadley, Amherst Notch, and Springfield. Collector F. H. Sprague did not have it on his comprehensive 1878 list (Sprague 1879). Although many other skippers were known in eastern Massachusetts at the turn of the century, Little Glassywing had not been found. Like the Delaware Skipper in 1900, and the Zabulon Skipper today, Little Glassywing seems to have first arrived in the state by moving up the Connecticut valley.
Photo: Amity Place, Amherst, Mass., F. Model, July 10, 2007
Little Glassywing was first described and named by W. H. Edwards from an Illinois specimen; surprisingly it was not named for a Native American.. Its range is very similar to that of Northern Broken-Dash, though a little more restricted at the southern and northern extremes (Opler and Krizek 1984; Cech 2005). Recent records from the Maine Butterfly Survey show Little Glassywing found in only a few towns along the southern coast, (where it may have arrived but recently, since there are no historical records). By contrast Northern Broken-Dash is found in slightly more towns in southern Maine, and there is one recent record for Northern Broken-Dash in central Maine (Maine Butterfly Survey 2010). Little Glassywing reaches Canada only in southern Ontario and along the border of Quebec, whereas Northern Broken-Dash is found much further into Canada (Layberry 1998).
Little Glassywing appears to have been expanding its range northward in the 20th century, like the Delaware Skipper. In New Jersey, a 1990’s review of historical sources indicates that this species was increasing there between 1890 and 1910, and by the 1990's was “more common today than a century ago" (Gochfeld and Burger 1997: 243). In his review of New England lepidoptera in the 1930’s, Farquhar (1934) still finds Little Glassywing “exceedingly rare,” but is able to cite one specimen from eastern Massachusetts: from Stoneham, caught by noted collector C. V. Blackburn. Otherwise, he knew only those western Massachusetts locations cited by Scudder. On Nantucket and Martha's Vineyard, Jones and Kimball (1943) did not find it, saying its putative presence was "not verifiable," and there are no mid-century specimens from these well-collected islands.
The earliest eastern Massachusetts specimens appear to be six collected in North Weymouth in 1936 by C. L. and P. S. Remington, and one each from Canton and Fall River that year (Yale Peabody Museum). By the 1940's, W. P. Rogers had collected quite a few from around coastal Bristol County--Fall River, Freetown and New Bedford (Yale Peabody Museum). Like several other species, Little Glassywing may have arrived in eastern Massachusetts separately, and later, than in the Connecticut River valley.
But by the 1960’s and 1970s, Little Glassywing was becoming more common in Massachusetts (Table 2). As an interesting new species, it was widely collected. Mark Mello found it in Rochester in July 1961 (Mello, pers. collection). C. G. Oliver found it in West Acton, Acton Center and Belmont 1956-1965 (Yale Peabody Museum). William D. Winter found it in 1966 in Dover, 1972 in Westwood, and 1974 in Millis and Sherborn and West Medway (specimens in the Harvard Museum of Comparative Zoology). Edward Peters took males and females in Carlisle in August 1970 and July 1971, and Darryl Willis reported Little Glassywing as “common” in July 1974 in the Holliston-Sherborn area (Lep. Soc. Seas. Sum. and Corresp. 1959-81). The species was also apparently moving into higher-elevation Berkshire County: L. F. Gall documented Little Glassywing on 9 July 1974, finding a specimen in Becket, and earlier--1947-- it had been found in New Marlborough on the Connecticut border (Yale Peabody Museum).
Host Plants and Habitat
The most widely reported host grass for Little Glassywing is Tridens flavus, known as Purpletop or Tall Redtop (Scott 1986; Opler and Krizek 1984; Cech 2005). Many sources report Purpletop as the sole host grass, however, as Leahy points out in the MAS Atlas, this is a somewhat uncommon and locally distributed plant in Massachusetts, and given that Little Glassywing is now quite common and widespread here, Little Glassywing most likely uses other grasses here. Tridens flavus was introduced to nearly all Massachusetts counties from further south (Sorrie and Somers 1999), and perhaps Little Glassywing increased here as this grass has become more common. It is still not a common grass in either Berkshire or Bristol Counties (Magee and Ahles 1999).
The Connecticut Atlas did not find eggs or larvae in the wild, but raised Little Glassywing in the lab on Tridens flavus, Schizachryrium scoparius (Little Bluestem), and Dactylis glomerata (Orchard Grass). Field evidence is needed to determine what the natural host grass is today in our area, but all of these grasses are likely candidates.
Little Glassywing’s preferred habitat is widely reported to be both moist meadows and woodland roads and edges (O’Donnell et al 2007; Cech 2005; Opler and Krizek 1984; Layberry 1998; Shapiro 1974). In moist meadows, it is often found flying along with Northern Broken-Dash and Dun Skipper and nectaring on common and swamp milkweeds, vetch, dogbane, self-heal, and perennial pea. However, the purported sole larval host plant, Purpletop, is a facultative upland grass, occurring most often in dry sandy woods and woods edges (Magee and Ahles 1999; Leahy, Atlas), and Little Glassywing may particularly use areas near woodlands for larval feeding.
Little Glassywing is hard to find on Cape Cod and evidently not present on the Islands in Massachusetts, and in fact is generally rarer on the outer coastal plain of eastern United States than inland (Cech 2005). It is rare in the sandy pine plain areas of southern New Jersey, even where Purpletop grass is common (Gochfeld and Burger 1997:243). Cech speculates that “perhaps the grass is more fire-tolerant than the butterfly.”
It seems safe to say that Little Glassywing probably utilizes all types of grassy open areas, wet, mesic and dry, for nectar and larval hosts, but may particularly need inland dry areas for larval hosts. NatureServe (2010) says that it is “not usually seen far from trees,” but its habitat “may vary regionally.” Cech (2005) classes Little Glassywing as an adaptable meadow-habitat generalist.
Relative Abundance Today
Whereas the Atlas had termed Little Glassywing “Common,” MBC Sightings 2000-2007 rank it as “Uncommon-to-Common,” about on a par with Long Dash, Tawny-edged, and Hobomok Skippers, and less common than Northern Broken-Dash (Table 5). It is not reported in anywhere near the same numbers as Peck’s Skipper, which is ranked Common, and is less common than the next most numerous skippers, Least and Dun Skippers. However, as noted, Little Glassywing has almost certainly increased in abundance since Scudder’s time.
There is a broad upward trend in MBC sightings per trip reports shown in Chart 97. Little Glassywing is one of several grass skippers to show an increase in sightings over this period; the others are Arctic Skipper, Least Skipper, Tawny-edged Skipper, Northern Broken-Dash, and Dusted Skipper.
Chart 97: MBC Sightings per Total Trip Reports, 1992-2009
In Chart 97 the reading for 1997 is artificially high and should probably be lowered. It results mainly from an unusual report of 85 from the Outer Cape NABA count, which was not approached in subsequent years and probably should be adjusted downward.
State Distribution and Locations
Map 97: MBC Sightings by Town, 1992-2009
Map 97 shows 1992-2009 MBC records of Little Glassywing from 108 out of a possible 351 towns in Massachusetts; records through 2011 show 125 towns, including Cheshire, Hadley, Monson, New Marlborough, Sturbridge, Wales, Ware, Wendell, Whately, and Windsor in central and western Massachusetts. This skipper is now well distributed across the state, and is regularly found on most of the NABA July Counts, including the three Berkshire County Counts but excepting Martha’s Vineyard and some of the Cape Cod Counts.
Interestingly, Little Glassywing appears to be still generally absent from Nantucket and Martha‘s Vineyard. MBC has no records for either island. For Nantucket, the Atlas had one record (7/10/1991 J. Anderson), but recent observers have not found it (LoPresti 2011). The Martha’s Vineyard checklist does not list Little Glassywing at all--- in contrast to Northern Broken-Dash, which is listed as “Common” on the Vineyard (Pelikan 2002).
Mark Mello did not find Little Glassywing on his 2001-2 survey of the Boston Harbor Islands, nor on the Elizabeth Islands (Mello 2003; 1988). Perhaps the dry woodland-edge habitat (see above) is in short supply on coastal islands.
The 1986-90 Atlas had found Little Glassywing less common on Cape Cod than elsewhere. MBC records support the same conclusion, showing very few recent reports from Cape Cod. In the late 1990’s, some unusually large numbers were reported from the Outer Cape (Truro) area on the NABA Counts, but they seem likely to have been either exaggerations or misidentified Northern Broken-Dashes. There have been NO reports of Little Glassywing on the Truro count since 1999, through 2011, and the count has been held every year. Since 1999, the species has only twice been reported on the Falmouth count, in 2010 and 2011, and sparingly at other times from Falmouth. Mello and Hansen (2004: 64) say Little Glassywing can be regularly seen at Fort Hill, Higgins Windmill, and Webster Farm Conservation Area on the Cape.
Little Glassywing is noticeably less common on the three Berkshire County NABA counts than on the mid-state counts; it is reported almost every year from the Berkshire counts, but numbers are comparatively low. In contrast, Little Glassywing has been reported every year 1992-2009, and in very good numbers, from the Central Franklin count (max 46 on 7/4/2004), and almost every year in good numbers from the Northern Worcester 1996-2009 (max 48 on 7/11/2004), North Essex 1998-2009 (max 36 on 7/8/2007), Blackstone Valley 2001-2009 (max 63 on 7/14/2007), Concord 1992-2009 (max 33 in 1996), and Foxboro 1992-2000 (max 47 in 1999) Counts.
Little Glassywing is usually found in small to medium numbers at any one site. Some high counts from selected locations are
Amherst max 8 7/1/2007 Amity Place environs F. Model; Athol max 14 on 7/14/1996 D. Small; Boston max 5 on 7/15/1996 B. Malcolm; Canton Great Blue Hill max 13 on 7/8/2006 M Champagne and E Nielsen; Charlton max 14 on 7/26/1997 R. Hildreth; Cheshire max 12 on 7/9/2011 B. Benner; East Longmeadow max 7 on 7/7/2007 K Parker; Grafton Dauphinais Park max 6 on 7/6/2007 D. Price; Harvard Oxbow NWR max 5 on 7/18/2004 T. Murray; Leicester max 6 on 7/30/2003 M. Rowden and E. Barry; Lexington Great Meadows max 4 on 7/5/1997 M. Pelikan; Milford max 5 on 7/16/1999 R. Hildreth; Monson Norcross WS max 10 on 7/14/2011 E. Barry; New Marlborough max. 12 on 7/8/2011 B. Benner; New Salem Prescott Peninsula max 5 on 7/9/1998 D. Small; Newbury Martin Burns WMA max 8 on 7/8/2007 B. Walker et al., and Old Town Hill TTOR max 24 on 7/2/2011 E. Nielsen; Newburyport Maudslay SP max 16 on 7/10/2007 S. and J. Stichter, Water Tower max 25 on 6/26/2010 B. Zaremba; Northampton community gardens, max 8 on 7/24/2007 F. Model; Sharon Moose Hill Farm TTOR max 33 on 7/12/2009 E. Nielsen; Truro Horton's max 8 on 7/17/1999 A. Robb and B. Nikula; Upton Robertson's gas line, max 11 on 7/4/1999 T. and C. Dodd; West Newbury Mill Pond Rec area, max 14 on 7/3/2005 S. Stichter et al.; Williamsburg Graves Farm max 15 on 7/1/2011 B. Benner et al.; Williamstown max 11 on 7/15/2009 B. Zaremba, and Mountain Meadow Preserve TTOR max 4 on 7/5/2008 P. Weatherbee; Woburn Horn Pond Mountain max 5 on 7/8/2006 S. Moore and B. Volkle, and 5 on 7/5/2009 M. Rines et al.; Worcester Broad Meadow Brook WS, max 6 on 7/14/2003 B. Walker.
Broods and Flight Time
The midseason univoltine skippers, such as Little Glassywing and Northern Broken-Dash, are more common and seem to have an easier time of it than the early and late season species with only one brood, like Cobweb and Leonard’s. Like Northern Broken-Dash, Little Glassywing has one long midsummer brood, but starts to become commonly seen a little earlier than the former.
Scudder (1889:1745) wrote of this species that “The earliest butterflies make their appearance the very last of June---sometimes as early as the 22nd, but it is not until about the 4th of July that the insect becomes abundant and it flies throughout this month.” He seems to have been generally referring to the lower Connecticut River valley in Massachusetts, and Connecticut, where his specimens were from.
The earliest Little Glassywings are now being seen in the second week of June, rather than the last week, as in Scudder’s day, or as reported in the Atlas. In 7 of the 19 years 1991-2009, the first sightings of Little Glassywing have been June 15 or earlier; in 2 years they were in May. (The Atlas early date was also in early June: 6/4/1987, Milford, R. Hildreth.) These seven earliest MBC sightings are 5/24/2004 East Longmeadow, K. Parker; 5/28/1998 Northampton Florence T. Gagnon; 6/4/1999 Paxton, E. Barry; 6/10/2000 Westwood Hale Reservation E. Nielsen; 6/10/2007 Sherborn power line B. Bowker; 6/12/1996 Hampden G. Howe; and 6/15/1991 Princeton Wachusett Meadow WS. The rest of the first sightings in these years are in the last week in June, and the flight peaks in the first three weeks of July, tapering off after that, and ending by the end of August (http://www.naba.org/chapters/nabambc/flight-dates-chart.asp).
We do not usually see this species flying into September. The five latest MBC sighting dates are 9/7/2008 Northampton Community Gardens, T. Gagnon; 8/29/1992 Worcester T. Dodd; 8/28/2005 Canton Great Blue Hill E. Nielsen; 8/25/2009 Sherborn power line B. Zaremba; and 8/24/1998 Mansfield R. Hildreth. Scudder had suggested the flight ended at the end of July; MBC records still show good numbers seen through the first three weeks of August.
Outlook
Little Glassywing may be slightly less adaptable to a northern climate than Northern Broken-Dash, since it does not presently extend as far into Maine, New Hampshire, and Canada. However, it ranges throughout southeastern United States, and should be able to adapt to climate warming in the northeast and perhaps increase in numbers here (Table 6). In warmer climates, Little Glassywing does produce two broods. Glassberg (1993) reported an occasional partial second brood in August in the Philadelphia area, but that has not been observed in New Jersey (Gochfeld and Burger 1997) and Shapiro (1966) reported second broods only as far north as Virginia. Still, evidence of full or partial second broods in our area should be watched for.
Conservation and proper management of open dry and wet meadows is necessary to provide habitat for this and many other skippers. Grassy areas that are mowed more than twice a year, such as most lawns, golf courses, and city parks, do not provide habitat (NatureServe 2010; see also MBC Conservation page http://www.naba.org/chapters/nabambc/butterfly-conservation.asp ) . Little Glassywing has a single brood whose larvae will be feeding on grasses in late summer and early fall, and then probably overwintering at the soil surface. A single mowing in late fall, with the cutting blade set on high, should allow some larvae to survive in a field, overwinter, and resume growth in the spring. Mowing during flight time and active larval feeding in spring and summer is counter-productive.
© Sharon Stichter 2011, 2012
page updated 1-7-2012
ABOUT BOM SPECIES LIST BUTTERFLY HISTORY PIONEER LEPIDOPTERISTS METHODS