ABOUT BOM SPECIES LIST BUTTERFLY HISTORY PIONEER LEPIDOPTERISTS METHODS
The Butterflies of Massachusetts
74 Northern Cloudywing Thorybes pylades (Scudder, 1870)
Thaddeus W. Harris at Harvard was the first to distinguish the Northern Cloudywing, but he called it a local variation of the Southern, which had been figured by John Abbot and named by J. E. Smith in Insects of Georgia, published in 1797. It remained for Scudder to establish Thorybes pylades as a separate species, and to point out that Harris’ figure was identical to it (Scudder, 1872).
The southern T. bathyllus was well known to early entomologists. Harris, in the expanded 1862 edition of his report on injurious insects, wrote “In Massachusetts we have what I suppose to be only a local variety of the Bathyllus skipper, differing from Southern specimens in the inferior size of the white spots on the fore wings, the less prominent hind angle of the hind wings, and the darker color of the fringes.” (1862: 312, Fig 135). As Scudder determined, the description and figure accord with the Northern, not the Southern Cloudywing.
Photo: Norwottuck rail trail, Amherst, Mass. F. Model 6-17-2005
The Northern Cloudywing “ has been found everywhere in New England in abundance from Nantucket and Connecticut in the south to the White Mountains and Maine in the north, in elevated stations as well as on the plains,…” wrote Scudder in the 1880's (1889: 1441). It had probably greatly increased as forests were cleared for agriculture after 1600 (Table 1). Similarly, Maynard (1886) referred to what he called the Dark -brown Tailed Skipper: “This is a very common species in Massachusetts, being found on flowers in June and July, and though a restless species, may be easily captured.” Maynard was referring to the Northern Cloudywing, because he says “this is the Bathyllus of Harris.” The Southern Cloudywing, on the other hand, was “not the bathyllus of Harris;” it was ”a rare skipper in Massachusetts only occurring, at least at all commonly, in the western portion of the state.”
Donald Farquhar, in his 1934 review of New England lepidoptera, found Northern Cloudywing still “general and very common.” F.H. Sprague collected many specimens in Wollaston (now Quincy) in May and June, 1878, and some also in Belchertown (Sprague 1879). He collected it at Milton Blue Hills in 1883, C. A. Frost collected it in Stoneham and Framingham in 1903 and 1904, and C. W. Johnson collected it in Great Barrington in the Berkshires in 1919 (Boston University). On Martha's Vineyard, pylades was "apparently rare" but there were specimens from 1931, 1937, and 1940. On Nantucket, it was "well distributed but rather infrequent," with a specimen from 1925 (Jones and Kimball 1943; Boston University; LoPresti 2011).
Host Plants and Habitat
The Tick-trefoils (Desmodium) and the Bush-clovers (Lespedeza) are key plant genera for several butterflies, including the Hoary Edge, the Eastern Tailed-blue, and the Southern and Northern Cloudywings. There are many species of these genera in Massachusetts: Sorrie and Somers list 12 tick-trefoils, all native to most counties, of which Showy Tick-trefoil or Desmodium canadense is probably the most common and widespread ( Magee and Ahles 1999), and 8 native bush-clovers. Round-headed, ( L. capitata), Hairy (L. hirta), and Intermediate (L intermedia) bush-clovers are native to and found in all Massachusetts counties ( Magee and Ahles). Thus, the apparent declining trend in abundance of Northern Cloudywings (see below) does not seem attributable to any lack of host plants.
Northern Cloudywing also uses another interesting native plant, Hog Peanut, (Amphicarpaea bracteata) which may not be abundant today, but is native to all counties in the state, and found in all but Plymouth County (Magee and Ahles 1999).
The Northern Cloudywing’s preferred habitats are dry open upland habitats, including old fields, power lines, and forest edges, but it can also be found in moister areas.
Northern Cloudywing has been adept at using introduced host plants (Table 3, Switchers). Red Clover (Trifolium pratense) and Alfalfa (Medicago sativa) are among its host plants (Scott 1986); White Clover (Trifolium repens), Birds Foot Trefoil (Lotus corniculatus) and introduced vetches (Vicia spp.) are also reported. The adoption of imported clovers is reported as far back as the 1880’s: Scudder wrote that “The caterpillar probably feeds on almost any of the Leguminosae, but its common food appears to be Trifolium and Lespedeza. The common red and white clovers, T. pratense and T. repens, seem to be most sought (1889: 1441).”
The 1995-99 Connecticut Atlas found Northern Cloudywing eggs or larvae in the wild on Desmodium and Lespedeza spp. and on introduced vetch (Vicia spp.). Northern Cloudywing has not recently been reported as using clovers as other than a nectar source in Massachusetts.
Relative Abundance Today
MBC sighting frequencies 2000-2007 rank both the Northern and Southern Cloudywings as “Uncommon” in comparison to common species (Table 5). The 1986-90 Atlas found it in 82 of the 723 blocs searched, making it more frequently found than the Southern Cloudywing, (20/723 blocs), but still “Uncommon” in overall rank. The Atlas characterized it as “common,” but this does not seem warranted, since it was nowhere near as common as the American Lady (171/723 blocs) or the Silver-spotted Skipper (160/723 blocs). Our benchmarks for the term “common” should be species that the casual observer might easily come across.
The Northern Cloudywing is probably no longer as “common” as it apparently was in Scudder and Maynard’s time, if Scudder and Maynard in the late 1800’s were using the word “common” in the sense suggested here. However, it is still widespread, and can usually be found by the determined observer.
Chart 74: MBC Sightings per Total Trip Reports, 1992-2009
MBC sightings per total trip reports 1992-2009 indicate a decline in this species (Chart 74). The chart shows a strong downward trend since a peak in 1997. This is a different pattern from Southern Cloudywing (Chart 73), suggesting a lengthier decline.
A caveat, however, is that the high in 1997 is due to an unusual report of 56 in Mendon (6/8/1997, T. and C. Dodd), and the high in 1996 is mainly due to two reports a week apart of 26 each from Mendon (6/1/1996 and 6/8/1996, T. and C. Dodd.) There are no other reports from single locations in the records which exceed 25, not even from NABA Counts. If these Mendon reports were halved, a trend downward would still be present, but it would be much less dramatic.
State Distribution and Locations
Map 74 Northern Cloudywing Sightings by Town, 1991-2009
MBC records 1992 through 2011 show Northern Cloudywing in 113 towns across the state, as compared to only 63 for Southern Cloudywing. Northern Cloudywing is statewide, occurring in all counties west to east (Map 74). The distribution found by the 1986-90 MAS Atlas was broadly similar, but there are several notable changes.
The Atlas had found Northern Cloudywing uncommon to rare on Cape Cod and Cape Ann, and did not confirm it for Nantucket, Martha’s Vineyard, or large portions of southeastern Massachusetts.
Northern Cloudywing has now been quite thoroughly reported from Cape Ann by Doug Savich and Claudia Tibbits. These veteran butterfly watchers have reported good numbers of Northern Cloudywings from Gloucester and Rockport every year since 1994, a remarkable record. The high single-day counts were 19 in 2002 and 2003.
On Martha's Vineyard, the 1986-90 MAS Atlas did not find Northern Cloudywing, and Jones and Kimball (1943) had termed the species "apparently rare", but cited three specimens: 1931, 1937, and 1940. However, MBC now has many reports from West Tisbury and Edgartown, suggesting an increase in this species on the island since the 1930's. Local butterfly observer Matt Pelikan has reported singles from West Tisbury and from Edgartown State Forest nearly every year from 1998 to 2003, including 2011. Northern Cloudywing is listed as Uncommon on the Martha’s Vineyard checklist (Pelikan, 2002).
On Nantucket, Jones and Kimball (1943) had reported pylades as "well distributed but rather infrequent." The Atlas did not find it there, nor does MBC does have any records yet. But there are historical specimens in the Maria Mitchell Museum, and observers feel that this species as well as bathyllus is a likely candidate to be found on Nantucket (LoPresti 2011).
With regard to Cape Cod and lower southeastern Massachusetts, the Atlas finding of “uncommon” is largely corroborated by MBC records. Since 1990, neither Northern nor Southern Cloudywing has been frequently reported from these areas. The Falmouth NABA Count has not reported Northern Cloudywing since 1999, although it reported Southerns from Crane WMA in 2005, 2006 and 2007. There are no records from the other Cape NABA Counts (Truro, Barnstable and Brewster, all in existence since 2004) except for a report of 4 from the Brewster Count in 2007. Northern Cloudywing has never been reported from the Bristol NABA Count (located primarily in Dartmouth and Westport), although in 2004 that Count had one Southern Cloudywing. There is a single record from the Dighton power line and singles were found for several years on the Middleboro NABA Count.
The NABA Counts from which Northern Cloudywing is reported most frequently are Central Franklin (most years, max. 7 in 7/8/2006), Foxboro (most years in the 1990’s, max. 8 on 7/6/1997), and Northern Worcester (max. 7 on 7/6/2008).
Locations which have been most productive for Northern Cloudywing include
Worcester Broad Meadow Brook WS, many reports, max. 25 on 6/4/2000 G Howe + B Bowker; Grafton Dauphinaise Park, many reports, max. 21 on 6/10/2007 D Price et al.; Hopedale Draper Park max. 13 on 6/10/2002 B. Bowker; Princeton Wachusett Meadow WS max 10 on 6/4/2011 C. Kamp et al.; Leominster Doyle Reservation TTOR max 10 on 6/2/2010 R. Hopping; Newbury Martin Burns WMA, max 9 on 6/16/2004 T. Whelan; Williamstown Mountain Meadow max. 9 on 6/18/2011 B. Zaremba; Upton Chestnut St. gas line, max 6 on 6/13/1999 T. and C. Dodd; Gloucester Industrial Park, max 10 on 6/5/1999 D. Savich and C. Tibbits; Mansfield Maple Park, max 6 on 6/14/2001 R. Hildreth; and Petersham North Common Meadow TTOR max 6 on 6/20/2011 G. Breed and P. Severns.
Other productive locations have been Boston West Roxbury Millennium Park; Falmouth Crane WMA, Hingham World's End TTOR, Sharon Moose Hill TTOR; North Andover Weir Hill TTOR; and Ware Muddy Brook WMA.
Broods and Flight Period
According to MBC 1993-2008 records, Northern Cloudywing flies from mid-May to the first week in August (http://www.naba.org/chapters/nabambc/flight-dates-chart.asp). This is slightly longer than the flight period for Southern Cloudywing. There is probably only a single brood, although the species should be watched for a partial second brood.
In 20 years of MBC records (1991-2010), three years had first sightings prior to May 15: 1 May 2010 Barre M. Lynch and S. Carroll; 10 May 1999 Cape Ann, D. Savich and C. Tibbits; and 31 May 2001 Sunderland, T. Gagnon. An additional four years had first sightings between May 15 and 21: 5/16/2009 Groton, T. Murray; 5/19/2003 Cape Ann, D. Savich and C. Tibbits; 5/19/2004 Andover Ward Res. F. Goodwin; and 5/21/2000 Cape Ann, D. Savich and C. Tibbits. The remaining 13 first sightings were in the last week of May.
The main tendency (mean or average) first flight timing seems little different from Scudder’s 19th century report: “It first appears as a butterfly toward the end of May, rarely earlier than the 24th and usually not until the 27th or later (1889: 1442-3).” However, the number of reports in the first, second and third weeks of May is more frequent today than Scudder's account would suggest. Such early flights are now more than just "rare." [Interestingly, F. H. Sprague first saw a Northern Cloudywing on the 7th of May 1878, in Wollaston (Sprague 1879), the "rarity" to which Scudder may have been referring.]
In these 20 years of MBC records, there are two August late flight dates: 8/5/2008 Sherborn Rocky Narrows TTOR, B. Bowker, and 8/2/2004 Newbury Martin Burns WMA, S. and J. Stichter. In 7 years, the last sighting date was the last week in July, and in 5 years, the third week in July.
Taken as a whole, these late dates in MBC records are later than those suggested by Scudder, who said that “a few always linger on until at least the middle of July and in elevated districts until the end of July (1889: 1442-3).” Whether these late sightings indicate a partial second brood, as Scudder believed, or simply a longer flight period, is still not established.
About broods, Scudder wrote “...the second brood of butterflies, which is much less abundant than the first (probably because many chrysalids continue until the next spring), appears in August, perhaps sometimes as early as the beginning, but usually not before the middle of the month (my emphasis), continuing upon the wing until past the middle of September; whether the progeny of this brood reaches the chrysalis stage before winter approaches has never yet been determined: if not it probably perishes (1889:1443).”
Mello and Hansen (2004) suggested a partial second brood on Cape Cod, and Layberry (1998) reports a partial second generation in August in extreme southwestern Ontario. But the Connecticut Atlas reports “one generation, late May to early July” (O’Donnell et al. 2005). Evidence for Massachusetts is lacking.
The mild decline in Northern Cloudywing, if it is one, is not easy to explain. Northern and Southern Cloudywings are sympatric over much of their continental range, with T. pylades having a wider, more northerly range (well into Maine, New Hampshire and Vermont), and being found more often in woodlands and higher elevations, but coexisting with T. bathyllus in many areas. It does not seem likely that an increase in populations of Southern would pose competitive pressures for the Northern. The Northern’s range also extends well southward, where it has 2-3 broods, so that climate warming does not seem a factor that would produce decline.
Climate warming here would increase the likelihood of a partial second brood, and observers should be on the alert for this possibility. Population trends in both Northern and Southern Cloudywings in Massachusetts need better monitoring.
Cech and Tudor (2005) classify Northern Cloudywing as an adaptable “generalist” species. The Connecticut Atlas found no change in the status of this species. Its NatureServe (2010) rank in Massachusetts is S5, or secure.
© Sharon Stichter 2010, 2011, 2012
page updated 2-15-2012
ABOUT BOM SPECIES LIST BUTTERFLY HISTORY PIONEER LEPIDOPTERISTS METHODS