Lepidoptera of Fort Indiantown Gap National Guard
Training Center, Annville, Pennsylvania
Betty Ferster, Betsy Ray Leppo, Mark T. Swartz, Kevina Vulinec,
Fred Habegger, and Andrew Mehring
Northeastern Naturalist, Volume 15, Issue 1 (2008): 141–148
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2008 NORTHEASTERN NATURALIST 15(1):141–148
Lepidoptera of Fort Indiantown Gap National Guard
Training Center, Annville, Pennsylvania
Betty Ferster1,2,*, Betsy Ray Leppo3, Mark T. Swartz1,2, Kevina Vulinec4,
Fred Habegger1, and Andrew Mehring1,5
Abstract - Eighty-one species of butterflies and two-hundred and thirty-seven species
of moths were identified from Fort Indiantown Gap, a National Guard training
facility in south-central Pennsylvania. The Lepidoptera found here include the last
remaining population of Speyeria idalia idalia (eastern regal fritillary), as well as the
rare Callophrys irus (frosted elfin), Hesperia leonardus (Leonard’s skipper), Datana
ranaeceps (hand-maid moth), Zale sp. 1 nr. lunifera (Pine Barrens zale), and Anisota
stigma (spiny oakworm moth). This habitat has a large and diverse Lepidoptera
fauna, most likely due to periodic disturbance in some areas, conservation efforts to
maintain native grassland, and a diverse plant community.
Lepidoptera can be charismatic insects that often attract attention from
naturalists and scientists for esthetic, ecological, and conservation reasons
(Glassberg 1999, Hogsden and Hutchinson 2004). Butterflies have also been
used as indicators of ecosystem diversity and health (Blair 1999, Brown and
Frettas 2000, Gilbert 1984, Kremen 1992, Murphy et al. 1990, Noss 1990,
Pyle et al. 1981, Swengel 1998). Military installations, due to their training
requirements, are often large parcels of land that harbor habitats that act as
refugia for wildlife. Species inadvertently protected on such parcels may be
rare in other parts of their natural range because of habitat destruction or
fragmentation. Fort Indiantown Gap National Guard Training Center (FTIG)
is an approximately 7500-ha parcel that has been used by the military for
training purposes of various types since 1931 (TNC 2000). Now protected
from most land-use practices that have led to the demise of many species
in other parts of the Northeast, this property provides a last refuge for species
that require a sustainable grassland ecosystem, maintained by periodic
disturbances, followed by periods of inactivity that allow for recovery. This
study, which began as a flora and faunal study in 1999, was initiated as part
of an ongoing mission to inventory biodiversity on Department of Defense
1The Nature Conservancy, Fort Indiantown Gap Office, Environmental Unit, Building
11-19, Annville, PA 17003-5002. 2Shippensburg University, Department of
Biology, 1871 Old Maine Drive, Shippensburg, PA 17257. 3Western Pennsylvania
Conservancy, Pennsylvania Science Office, 208 Airport Drive, Middletown, PA
17057. 4Delaware State University, Department of Agriculture and Natural Resources,
1200 North DuPont Highway, Dover, DE 19901. 5Current address - Odum
School of Ecology, University of Georgia, 1049 College Station Road, Athens, GA
30602-2202. *Corresponding author - email@example.com.
142 Northeastern Naturalist Vol. 15, No. 1
land. Additions to this list were added during yearly field work to monitor
the last remaining population of Speyeria idalia idalia Drury (eastern regal
fritillary butterfly) (Williams 2001) there.
FTIG, established in 1931 and located in south-central Pennsylvania
(Fig. 1), has been continuously used by various branches of the military for
training, including armored vehicle maneuvering, firing practice, infantry,
and aircraft training. It is the second-busiest National Guard installation in
the country, training more than 193,121 troops during 2002. These numerous
activities lead to periodic soil disturbance and repeated small fires that
act to maintain a large mosaic of grasslands dominated by native vegetation
(Latham et al. 2007). These grasslands support what appears to be the only
remaining population of eastern regal fritillary butterfly, and may support
other grassland specialist species as well. Between 1992 and 2004, researchers
with The Nature Conservancy (TNC), in cooperation with the military,
conducted field research to monitor the eastern regal fritillary butterfly.
Approximately 101 ha of grassland habitat have been set aside to protect
this population. Land management designed to prevent invasion of woody
Figure 1. Map of Fort Indiantown Gap, Dauphin and Lebanon counties, PA, with
training areas delineated and identified. Collection sites are indicated by collection
method; circles are locations of black-light traps, stars indicate locations of
daytime sweeps with insect nets, and triangles indicate a location where both collection
methods were used. Regal fritillary sites in training areas B-12, D-3, D-1,
and C-8 are restricted from most military activities; motorized vehicle use in these
areas is limited.
2008 B. Ferster, B. Ray Leppo, M.T. Swartz, K. Vulinec, F. Habegger, and A. Mehring 143
and exotic invasive plant species has resulted in a stable population of this
butterfly. In addition to these grassland habitats, FTIG is also extensively
forested, contains 119 ha of wetland habitat (AMEC 2006), and is home to at
least six species of rare plants (AMEC 2006). FTIG also supports rare vertebrate
species including Neotoma magister Baird (Allegheny woodrat) (Hart
2002, TNC 2000), Myotis septentrionalis (Trouessart) (long-eared Myotis),
Lynx rufus (Schreber) (bobcat) (TNC 2000), Crotalus horridus L. (Timber
Rattlesnake) (Reinert 1999; B. Ferster and M.T. Swartz, pers. observ.), Heterodon
platirhinos Latreille in Sonnini and Latreille (Eastern Hog-nosed
Snake) (TNC 2000; B. Ferster and M.T. Swartz, pers. observ.), and Agkistrodon
contortrix mokasen Palisot de Beauvois (Northern Copperhead) (TNC
2000; B. Ferster and M.T. Swartz, pers. observ.). The site also contains a
healthy and diverse Lepidoptera fauna. Butterfly and moth species have been
inventoried at FTIG since 1992, and in 1999, TNC was contracted to conduct
a flora and fauna survey for FTIG (Barton 1996, TNC 2000), which resulted
in a concerted effort to search for rare Lepidoptera species.
Survey sites were chosen to best represent the variety of habitats found
on the FTIG installation (Fig. 1). The sixteen black-light sites included
Quercus spp. (oak) and Acer (maple) forest; oak and Pinus spp. (pine) forest;
Fraxinus (ash), Carya spp. (hickory) and oak forest; Tsuga (hemlock) forest;
disturbed forest dominated by small pines; open grassland; and Acer rubrum
L. (red maple) swamp bordering an old field. The understory at forested sites
was dominated by Vaccinium spp. (blueberry), Hamemelis virginiana L.
(witch hazel), Lindera benzoin (L.) Blume (northern spicebush), Viburnum
prunifolium L. (blackhaw), and Rosa multiflora Thunb. ex Murr. (multiflora
rose). Ground cover consisted predominantly of Dennstaedtia punctilobus
(Michx.) T. More (hay-scented fern). During May–September 1999, a total
of seven nights (17–18 May, 15–16 June, 8–9 July, 14–15 July, 11–12 August,
8–9 September, and 1–2 November) were spent collecting night-flying
Lepidoptera. Two to three sites were sampled per night, using one black-light
trap per site. Trapping coincided with optimal collecting conditions; moths
fly most actively around the time of a new moon, so trapping nights were
set as close to a new moon as possible. Weather conditions were monitored,
and severe conditions avoided. Black-light traps consisted of two 15-Watt
black lights set over a funnel trap with trichloroethylene as a killing agent.
The traps were connected to a 12-volt battery and operated overnight. Specimens
were collected the following morning, removed from the trap, placed
in plastic bags, and kept in a cooler until they could be pinned and spread
for identification. On one trap night (8 July), military activity dictated that a
trap not be left out all night; so instead, in two sites, one at the north end of
144 Northeastern Naturalist Vol. 15, No. 1
training area C-4, the second in training area B-4 (Fig. 1), two black lights
were hung over a translucent 1.2- x 1.8-m white sheet and specimens were
collected by hand as they landed. After collection, specimens were sorted,
examples of each species were spread and pinned for identification and kept
as voucher specimens. Most voucher specimens have been deposited in the
collection of The State Museum of Pennsylvania, Harrisburg, PA. Voucher
specimens of species of special concern, as well as all common species collected
during the original 1999 survey, are located in the collection of the PA
Natural Heritage Program (The Western Pennsylvania Conservancy Science
Office) in Middletown, PA.
During 1999, as part of a flora and fauna survey for species of special
concern on FTIG property, a search for butterflies and skippers of special
concern was conducted. Seventeen sites that met the basic habitat requirements
for previously undocumented species of special concern at FTIG
were selected and surveyed. These sites included grassland (designated
regal fritillary, Speyeria idalia, habitat); areas that contained the food or
nectar plants of rare species including Baptisia tinctoria (L.) R. Br. ex Ait.
f. (yellow wildindigo), of Callophrys irus Godart (frosted elfin, [caterpillar
foodplant]); Potentilla canadensis L. (dwarf cinquefoil, a nectar plant for
skippers), and Quercus ilicifolia Wangenh. (scrub or bear oak, food plant
for Hemileuca maia Drury [eastern buck moth]); and a site with a seepage
area with sedges for Euphyes conspicua W.H. Edwards (black dash).
Areas with blooming plants (potential nectar sources) were also surveyed.
When possible, surveys were conducted between 0900 and 1600 hrs and
under favorable weather conditions (sunny, with temps ranging between
24–38 °C (75–100 °F) and wind speeds 16 kph (less than 10 mph). In subsequent
years, common as well as uncommon butterfly species were noted when
seen. Researchers spent much of the field season, from late March until
mid-October, collecting data on the life history and habitat use of S. idalia,
and so spent a great deal of time in the grassland habitat noting presence
of Lepidoptera species. At a number of roadside mud puddles near open
areas, puddling behavior was observed often and presented an opportunity
to identify congregating butterflies. On a few occasions, Lepidoptera
specimens were inadvertently collected in traps set out for collection of
other insect fauna (e.g., pan traps set for bees, pit-fall traps set for beetles).
Voucher specimens were taken for many of these species and have been deposited
in the State Museum of Pennsylvania collection.
Three hundred and eighteen Lepidoptera species were recorded from
FTIG during this study, including 81 species of butterfly and 237 species
of moth (Supporting Table 1 [available online at http://dx.doi.org/
2008 B. Ferster, B. Ray Leppo, M.T. Swartz, K. Vulinec, F. Habegger, and A. Mehring 145
10.1656/N621.s1]). Four butterfly species of special concern were found
at FTIG: Hesperia leonardus Harris (Leonard’s skipper), frosted elfin,
black dash, and eastern regal fritillary. An unexpected species, Danaus
gilippus Cramer (queen), was also reported, though no voucher specimen
was taken for verification. A single D. gilippus was seen 2 August
2002 (M.S. Swartz pers. observ.), but not collected, and thus this record
cannot be verified. Danaus gilippus feeds on Asclepias spp. (milkweed),
which is abundant at FTIG (B. Ferster, unpubl. data). This species has
also recently been found in New Jersey (Moskowitz 2001), and these records
may indicate the beginnings of a range expansion. However, it may
instead have been an escapee from a butterfly house not far from FTIG
(Hershey, Dauphin County, PA). Anartia jatrophae Johansson (white
peacock) was also an unexpected find for this area. This butterfly feeds
on verbenas (Verbenaceae) as larvae, plants that are widespread at FTIG.
Three moth species of special concern were found: Datana ranaeceps
Guerin-Meneville (hand-maid moth), Zale sp. 1 nr. lunifera (Pine Barrens
zale), and Anisota stigma Fabricius (spiny oakworm moth). Restricted access
to collection sites on this busy military installation limited collection
efforts and precluded sufficient survey of microlepidoptera.
Fort Indiantown Gap is a large military training facility in south-central
Pennsylvania (Fig. 1), with one of the largest tracts of native-plant dominated
grassland in the Northeast. Not surprisingly, the site supports a diverse
Lepidoptera community. Lepidoptera are holometabolous species with complex
life histories that include a voraciously herbivorous juvenile stage and
a nectar-feeding adult stage. Butterfly and moth populations are expected to
be more diverse where plant diversity is higher, and where habitat disturbance
is limited (Kocher and Williams 2000). Habitat and plant diversity
at FTIG are high because disturbance to grassland areas is limited (Latham
et al. 2007). These disturbances (such as track vehicle training and small
accidental fires) differ in frequency from the more frequent disturbances experienced
by grassland habitats that are managed and maintained by yearly
mowing. It is likely the unique nature and periodicity of the disturbances that
result from military training activities at FTIG that maintain diverse habitats
and diverse plant and lepidoptera communities here.
Lepidoptera species listed by the Natural Heritage Program as critically
imperiled (S1) (spiny oakworm moth, frosted elfin, hand-maid moth,
eastern regal fritillary, and Pine Barrens zale), or vulnerable (S3) in the
commonwealth of Pennsylvania (Leonard’s skipper) were found. The spiny
oakworm moth uses oaks, which are common in wooded areas here, as a
host plant. The frosted elfin is a widespread species that is rare in all areas
(Shephard 2005). Its host plant, yellow wildindigo can be found at FTIG in
146 Northeastern Naturalist Vol. 15, No. 1
open wooded areas, although not in large numbers. A hand-maid moth was
an unexpected find here. Until this collection, this species was considered
historic (i.e., extirpated) in the state (SH). The hand-maid moth requires
mixed hardwood forests, hardwood-pine mixes, and scrubland-grasslandwoodland
mixes. Larvae are known to use Lyonia spp. (staggerbushes) and
Leucothoe racemosa (L.) Gray (fetterbush) as larval foodplants. It appears
that at FTIG hand-maid moth is using Lyonia ligustrina (L.) DC (maleberry)
as a host plant (D. Schweitzer, NatureServe, Port Norris, NJ, pers. comm.).
The hand-maid moth is sometimes referred to as the post-burn Datana
because succession plays a critical role in determining its habitat and occurrence
(Wagner 2005). It may persist at FTIG because of the periodic burning
that occurs here. Leonard’s skipper feeds on perennial grasses including
Schizachyrium scoparium (Michx.) Nash (little bluestem), a plant that is
abundant in the open, grassland areas at FTIG. The population of eastern
regal fritillary here is likely the last remaining population of the subspecies
(Williams 2001), and we suggest here that it should be afforded greater attention
and protection than it currently receives. This species may be tied
to grassland habitat that no longer exists as it once did except here. The
presence at FTIG of these rare species underscores the importance of large
protected and properly managed parcels of otherwise uncommon features of
the landscape of the Northeast. It is likely that the periodic disturbances that
result from military training at FTIG (such as large track vehicles and small
accidental fires) are inadvertently the types of disturbances that maintain
healthy grassland ecosystems in the Northeast. Track-vehicle disturbance
may mimic the disturbances once caused by now extinct megafauna—iron
bison, as it were. Small fires might be similar to those once set by Native
Americans and later by European settlers in order to clear areas to improve
wildlife forage and for other purposes. The frequency of disturbance that
each parcel might experience at FTIG (5 years or more, B. Ferster, unpubl.
data) differs greatly from the types and frequency of disturbance (yearly fall
mowing) that managed open habitat routinely undergoes, and more closely
approximates the historically natural mechanisms of grassland regulation.
Consequently, future research should focus on understanding the dynamics
of these disturbances on biodiversity. The rich lepidopteran biodiversity
observed at FTIG may prove to be a useful benchmark for such studies.
Dale Schweitzer identified most moths. Walter E. Meshaka, Jr. read early
versions of this article and made helpful suggestions. TNG-FTIG range-control
personnel provided us safe access to areas necessary for collection and research.
Erica Sussman, Susan Klugman, Sally Ray, Aura Stauffer, Dale Schweitzer, Jim
Dowdell, Lieutenant Mike Green, Daniel Bogar, Gylla MacGreggor, and Dave
Zapotok assisted with field work. This project was sponsored in part by the
Pennsylvania Army National Guard (Cooperative Agreement # DAHA36-01-2-
2008 B. Ferster, B. Ray Leppo, M.T. Swartz, K. Vulinec, F. Habegger, and A. Mehring 147
9001). The content of the information does not necessarily reflect the position or
the policy of the United States Government, and no official endorsement should
be inferred. Funding for this project was also provided by the Pennsylvania Department
of Military and Veterans Affairs.
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