Explanation of Species Accounts
One of the main goals of the New Jersey Butterfly Club website is to present a current picture of the status and distribution of New Jersey’s butterflies that can be easily updated periodically or as needed. The species list follows the North American Butterfly Association’s Checklist & English Names of North American Butterflies, Second Edition (2001), and includes detailed accounts of 114 full species of butterflies that have been reliably reported from NJ since 2015. Three NABA-recognized subspecies are also discussed. 'White Admiral' is included in the description of Red-spotted Admiral, and 'Summer' and 'Atlantic' azures are included in the description of Spring Azure.
The other main purpose of the website is to provide an easily accessible source of comprehensive information for professional biologists, photographers, amateurs, and students of all ages. We also hope that the website will spark an interest in butterflies in adults and children, and perhaps rekindle an engagement with these wonderful insects in other adults whose childhood fascination may have been eclipsed by other interests.
Each species account includes the following sections:
Identification: This section includes details about size, color, and pattern. When appropriate, differences between males and females, and top and bottom wing surfaces are included. In describing the size of a species, absolute measurements are provided for all species except hairstreaks, and comparative descriptions are often added. For example, we describe American Lady, which often basks with open wings, as being "Small—2 inches" (the average measurement from wingtip to wingtip when the butterfly has its wings fully spread) and "much smaller than the similarly orange Monarch" (a species that most people are very familiar with and can readily picture in their minds). For grass-skippers, which do not bask with wings flat, the size given is the length of the forewing. We describe all hairstreaks, most of which also do not bask and which fall within a narrow size range, as about the size of a thumbnail, which gives the observer a reference literally at hand. Bear in mind that within a species size can sometimes vary considerably between, and even within, sexes, and between broods. The following size categories are used: Tiny: ≤1.0"; Very small: 1.1-1.4"; Small: 1.5-2.0"; Medium: 2.1-3.0"; Large: 3.1-4"; and Very large: ≥4.1". All sizes used are the average measurements provided in Cech and Tudor (2005).
We also include, where useful, some other helpful identification tips such as flight behavior and preferred nutrient sources (e.g., flowers, sap, dung).
NJ Status and Distribution: Resident species are known to overwinter in New Jersey at some stage of their life cycle. Most butterflies in NJ are residents. Immigrant species do not overwinter but repopulate the state anew each year from the south. They may occur annually and in appreciable numbers, such as Common Buckeye, Variegated Fritillary, and especially Monarch, or may be seen in fewer numbers (or even miss a year), such as Little Yellow and Clouded Skipper. Strays from other regions of the country appear only rarely in NJ. They usually are seen in summer and fall and usually as single individuals or in very small numbers, such as Zebra Swallowtail.
Abundance is categorized as abundant, common, uncommon, or rare. Underlying all these categories is the assumption that that the observer visits an area of suitable habitat for at least half a day in good weather within the appropriate flight period—and the numbers cited should be taken as very rough estimates. Generally, a species described as abundant is likely to be seen in large numbers (more than 50) on most visits; a common species is also likely to be seen on most visits but in fewer numbers (10-30); an uncommon species might be seen on fewer than 50% of visits and/or in small numbers (1-5); and a rare species might be seen once or twice per year or not even every year. Sometimes “fairly” and “very” are used as modifiers. For example, the active observer might expect to see 5-10 individuals of a species that is described as fairly common. Of course, many species vary considerably in abundance from year to year.
Distribution is described as “throughout” the state (meaning all regions of the state but not necessarily every county), or as occurring only or primarily in North Jersey (from Mercer, Middlesex, and Monmouth counties north) or South Jersey (from Ocean and Burlington counties south). We have tried to be as precise as the available data allow. Many species are of local distribution, meaning that relatively few sites that appear to be suitable are actually occupied. Distribution by county is shown graphically for every species. These color-coded state maps also indicate the time period of every county record (pre- or post-2015), and the type of record (photograph or sighting). The pre-2015 records go back in some cases to 1992, when some club members began keeping daily butterfly notes. Records occurring in 2015 and later were obtained primarily from the Northern NJ Butterfly Sightings section of this website and the South Jersey Butterflies Log as well as observations found on the iNaturalist website. Club members augmented these data from unpublished information and photos.
A master summary list of species/county records is available. Please send any updates to Sharon and Wade Wander. Historical county distributions are compiled in the “Atlas of New Jersey Butterflies,” by Iftner and Wright (1996).
Species classified as Endangered, Threatened, or Special Concern by the State of New Jersey are so noted in red.
Habitat: This is a necessarily qualitative description of preferred habitats. Where appropriate, we distinguish between wetland and upland habitats, open versus wooded habitats, and mention disturbed environments where appropriate. We also indicate whether a species is likely to be attracted to flower gardens.
Flight Period: The time frame within which most adults of a species are flying and likely to be seen. Extreme dates are the earliest and latest dates an adult has been reported. For the most part these dates were derived from observations (primarily by club members) going back to 1992. For most species, these dates are given separately for North and South Jersey. Extreme dates are fluid and subject to change, especially given the effects of climate change. Therefore, a sighting of a species before or after its given extreme dates (especially by only a few days) should not be discounted. Conversely a sighting that exceeds an extreme date by several weeks may be a misidentification and should be documented with a photo if possible.
Caterpillar Food Plants: Several sources (see Resources) were consulted to determine at least the main plants in NJ that caterpillars are known to eat.
Overwintering Stage: We consulted several sources (see Resources) to determine the stage at which each species overwinters in NJ: egg, caterpillar, pupa, or adult.
Good Locations: We list a few sites where members have consistently found a particular species. All sites are public, most have easy access and parking, and some have public restrooms. Some of the more popular locations are linked to detailed site descriptions elsewhere on this website. However, almost any public land may worth exploring. Information on species (even common ones) and numbers of individuals seen from little-explored areas is important—and sharing your observations is an opportunity to make real contributions to our knowledge of butterfly distribution and abundance in NJ. Take photos if possible, and be sure to post your observations to the Recent Sightings page!
Comments: This section includes some facts, observations, and asides that the reader may find interesting.
Acknowledgements:
The Species Accounts were originally prepared by Sharon and Wade Wander in 2013 and updated by them in 2023. The 2013 accounts were extensively reviewed by Tom Halliwell, and Jim Springer also provided comments. In 2013 Dave Amadio reviewed most species and provided especially helpful input concerning South Jersey. Jack Miller provided similar assistance with South Jersey species in 2023. Information for these accounts (especially on overwintering life stage, and caterpillar food plants) was obtained from Cech and Tudor (2005), and Gochfeld and Burger (1997). We also referred to these and other sources (see Resources) in preparing other sections of the Species Accounts. Much of the information on status and distribution, habitat, flight period, and good locations comes from the personal experiences of the above authors and reviewers, from members’ observations reported to the Recent Sightings page of this website, and from the South Jersey Butterfly Project. Data on butterfly observations were also gleaned from field reports published in “The Pearly Eye,” a publication of the records of the NABA-New Jersey Butterfly Club from 2001-2011.