ABOUT BOM SPECIES LIST BUTTERFLY HISTORY PIONEER LEPIDOPTERISTS METHODS
The Butterflies of Massachusetts
86 Least Skipper Ancyloxypha numitor (Fabricius), 1793
In the mid-19th century in Massachusetts Thaddeus W. Harris was familiar with “this pretty species” and thought that it had not been described before (1862: 308), but in fact knowledge of this small skipper in the New World goes back to John Abbot in the 1700s in Georgia, who made the first drawing of it. It was later more fully described by the Danish naturalist Fabricius.
The Least Skipper, Peck’s Skipper, and Hobomok Skipper are the only skippers that Scudder described as “abundant” in Massachusetts in 1889. At that time, Least Skipper was only abundant in Massachusetts and southward; it had been found in only a few places further north (1889:1560). It was so common here that Scudder saw no need to list the location of specimens. But the well-known and prolific collector F. H. Sprague took several specimens in Wollaston (now Quincy) in 1878 on June 5, 6, 7, and 14, and some in North Leverett on August 5 (Sprague 1879). Maynard (1886) corroborates Scudder: “I have always found this species very abundant in the tall grass which skirts water courses, and they continue to fly from the first of July until late in August.”
Photo: Nantucket, Mass., F Model, August 15, 2008
An inhabitant of grassy wet meadows, this skipper seems, like other meadow skippers, to have benefited from the widespread land clearing of the agricultural era 1600-1850, despite the loss of some wetlands in this process (Table 1). It also seems to have remained common through the succeeding period of industrial development; there is not much evidence of any decrease 1850-1950. In his 1934 review of New England butterflies, Farquhar lists many locations in Massachusetts from which Least Skipper had been collected: “Stoneham, Amesbury, Forest Hills, Marshfield, Wollaston, Auburndale, Plymouth, Brookline, Beverly, Lawrence, Salem, Amherst, Nantucket, etc., etc.” In the 1930's and 1940's, F. M. Jones found Least Skipper to be "widely distributed and frequent" on Martha's Vineyard, and Charles Kimball found it "general, but infrequent" on Nantucket, "probably overlooked because of its small size" (Jones and Kimball 1943).
Host Plants and Habitat
“The butterfly frequents low marshy meadows and the borders of runlets passing through them, especially where half choked with wild grasses, or in neglected bottom lands in the moister spots, but especially next to running water,” wrote Scudder (1889:1561). Today the habitat is the same; low moist areas with grasses, including streamsides, ditches, and wet meadows.
Least Skipper uses a variety of grasses as host plants, a fact which may be one of the keys to its population success. Hosts include Rice Cutgrass (Leersia oryzoides), Panic Grasses (Panicum spp.), Bluegrasses (Poa spp.), Foxtail Grass (Setaria spp.), Cordgrass (Spartina spp.), and Marsh Millet (Zizaniopsis miliacea) (Scott 1986). As far as is known, it has not switched to any non-native grasses in the wild.
Least Skipper’s flight is often described as weak; more accurately, it is slow but non-stop. Scudder put it this way: “It has a feeble flight, never darting about from one spot to another like other Hesperidae, but moving in a leisurely, languid manner, skipping over the grass tops of a lane, or among the reeds of a marshy rill, in the most dainty manner possible...(1889: 1562).”
Relative Abundance Today
The Least remains our second most common native grass skipper, after Peck’s Skipper and before Dun Skipper (Table 5). (It's about as common as the forb-feeding Silver-spotted Skipper.) The Atlas found Least in 157 out of 753 atlas blocs, which would rank it as Abundant, although it was termed Common. MBC sightings 2000-2007 rank it as “Uncommon-to-Common,” as shown in Table 5.
For the period represented in MBC records, the introduced European Skipper surpassed Least, Peck’s and Silver-spotted Skipper in relative abundance, but that may change, as European is showing a sharp decline in recent years from its highs in 1996, 1997 and 2003.
In MBC sightings, Least shows a slightly increasing trend 1992-2009 (Chart 86). But the low numbers reported for 1992 and 1993 seem a bit unusual, and it could be that the longer-term trend for Least Skipper is fairly stable. Minimally, there is no suggestion of decline.
Chart 86: MBC Sightings per Total Trip Reports, 1992-2009
The year 1997 saw a population explosion on Cape Cod and Martha’s Vineyard, although not elsewhere in the state. The numbers reported from the Cape on single-day counts in August that year were extremely high: 86 in Falmouth Woods Hole, 50 in West Tisbury, 75 on Cuttyhunk Island, 45 in Truro and 400 in Provincetown --- and these are from multiple observers and are areas where the usual August reports are in single digits or less than 20.
There were also particularly large numbers reported in 2004 on all three of the Berkshire NABA Counts, suggesting a population high in that region that year.
State Distribution and Locations
Least Skipper has been found in 150 of a possible 351 towns in Massachusetts, according to MBC records 1992-2009. It is distributed throughout all regions of the state, and is regularly found on all the NABA Counts, although often only in single-digits, probably because it is between flights in mid-July. The counts with less frequent reports of Leasts are Bristol County and Boston. The Berkshire counts have consistently produced good numbers.
Interestingly, Least Skipper appears to be quite at home on islands. It has been reported from the Elizabeth Islands (Nashawena, Naushon, Cuttyhunk, and Penikese) both in Atlas years and in MBC records. In the Boston Harbor Islands, Mark Mello found it on 7/1/2002 on Calf Island, and the Atlas found it on Thompson’s Island in 1988. The Atlas found Least Skipper at Siasconset on Nantucket, and on nearby Madaket and Tuckernuck islands. MBC observers have also found it on Nantucket; see photo above. And Least Skipper is common on Martha’s Vineyard, according to MBC records and the Vineyard checklist (Pelikan 2002).
Broods and Flight Time
According to MBC records 1993-2008, Least Skipper flies from the last week of May to mid-October (http://www.naba.org/chapters/nabambc/flight-dates-chart.asp). Least has three full broods in Massachusetts, and indeed throughout most of its large range.
Here is what Scudder wrote about the spring emergence of Least Skipper in the late 1800’s: “It appears on the wing early in June, occasionally as early as the 1st but ordinarily not before the 7th in the southernmost parts of New England or the 10th or 12th in the vicinity of Boston; occasionally it is a little later (1889:1561).” Collector F. H. Sprague reported that the date of its first appearance in Wollaston (Quincy) in 1878 was June 5 (Sprague 1879).
Judging from Scudder's quite specific account, Least Skipper appears to begin flying earlier now than it did a century ago. In five of the 19 years 1991-2009, Least Skippers were first seen in May rather than June, in MBC records. These five earliest sightings were 5/4/1994 Truro North, T. Hansen; 5/25/2001 Sherborn power line, B. Bowker; 5/28/2006 Stow Delaney WMA, B. Walker et al.; 5/29/2004 Grafton Dauphinaise Park D. Price et al.; 5/29/2007 Belmont J. Forbes.
In another nine of these 19 years, the first sightings of Leasts were in the first week of June (June 1-7). So the majority (14/19) of first sightings have been before June 7. And since 2001, all first sightings have been either in May or the first week of June. The Atlas also listed the earliest sighting in those years as in May: 5/29/1987 Sheffield E. Dunbar.
In Scudder’s day Least Skipper continued to fly “nearly to the end of September, though in scanty numbers in the latter part of the month (1889: 1561).” In MBC 1991-2009 records, the majority (12 out of 19 years) of last sightings are in the month of October. Therefore Least Skipper appears to be flying later nowadays. In fact, since 2000, all last sightings but one have been in October.
Many of the latest sightings come from Cape Ann, Martha’s Vineyard, or the South Dartmouth/Westport coast. The latest five sightings are 10/16/1994 Gloucester, D. Savich and C. Tibbits (also reported in the MAS Atlas); 10/16/2006 Chilmark, A. Keith; 10/14/1995 Chilmark, A. Keith; 10/12/2008 Westport, M. Lynch and S. Carroll; and 10/11/1997 Eastham, B. Nikula.
Given its wide continental range --- from Nova Scotia and Quebec south to Florida and the Gulf coast states---one would not expect Least Skipper to be particularly adversely affected by climate warming in Massachusetts. (For species affected by climate change, see Table 6.)
Although the flight of Least Skippers may be “weak” in terms of speed and height, it is strong in terms of persistence and time line. These small butterflies therefore seem to be good colonizers of new habitat (NatureServe 2010). They have multiple broods, use a variety of host grasses, and the recent trend is flat or upward. The outlook for these skippers in Massachusetts is good, provided there is sufficient moist area habitat available.
© Sharon Stichter 2011, 2012
page updated 11-31-2012
ABOUT BOM SPECIES LIST BUTTERFLY HISTORY PIONEER LEPIDOPTERISTS METHODS