March 2017 - The Friends of the East Brunswick Environmental Commission are launching the first town-wide East Brunswick Butterfly Survey to better understand our butterfly fauna. We are calling on everyone in town (and anyone else that wants to visit) to become Citizen Scientists and help us document what butterflies occur in East Brunswick and where and when they were found.

We have set up an iNaturalist project called "East Brunswick Nature" for everyone to post their photos. The project can be found at  We are interested in any sightings anywhere in town, from backyards to our amazing parks.

The Friends will also be awarding a copy of the Kaufman Guide to Butterflies to two lucky Citizen Scientists selected randomly in the fall from anyone that submits a butterfly record to the iNaturalist East Brunswick Nature group.      




East Brunswick Butterfly Park Butterflies

This page is an Online Field Guide to the butterflies seen so far at the East Brunswick Butterfly Park. This is a work in progress and at least for now, the butterflies are in no specific taxonomic order.


Butterfly Park is located off Rues Lane and Winton Road and is connected to Great Oak Park.  Click here for a map

The East Brunswick Butterfly Park is the first municipal park in New Jersey, and perhaps the country, dedicated o the conservation and enjoyment of butterflies. The park consists of an 11-acre preserve adjacent to Great Oak Park and features a 1,000-foot long cinder trail lined by numerous plantings to attract butterflies, a 400-foot long meadow trail, 1,000 feet of woodland trails, an early successional field that is being managed to control invasive shrubs and to promote wildflowers and grasses and second-growth upland woods being manage for invasive species. All trails feature benches and signs. The park is also located along the township bike way and a bike rack is provided at the entrance near Great Oak Park. The park provides habitat for a wide diversity of wildlife species, including butterflies, and offers abundant opportunities for nature study and enjoyment.

The park is an ongoing project of the East Brunswick Environmental Commission and the Friends and has been constructed primarily through volunteer efforts and donations. Field guides and butterfly nets are available for public use at the entrance to the park, near the kiosk. Abundant opportunities exist for individuals and groups to assist with the park. Please check the Events calendar at for work days at the park.  


Eastern Comma and Question Mark

Eastern comma. This butterfly and the next one look very similar but are really easy to identify if you can simply get a look at the shiny white markings on the hind wings. This is the comma and it gets its name from the sideways comma (,) shaped mark on the wing. Compare it to the very similar Question mark below with a mark that resembles a question mark (?) turned on its side.

Here is a close up of both markings, Comma first, Question mark second:

This is the Eastern Comma with the wings open. It looks very much like the Question Mark, but the Question Mark has a few extra black markings on the wing. For beginners, the best way to identify these two species is to try and get a good look at the comma or question mark on the undersides of the wings.

Gray Hairstreak

This next butterfly is a Gray hairstreak. It is one of three common hairstreaks at the Butterfly Park (The others are the Red-banded Hairstreak and the Coral Hairstreak). The Gray hairstreak is named for the true gray color of the wings, unlike other hairstreaks that are more grayish brown. The hairstreaks are all small (about 1\2") and look generally similar, but with a good look they can be easily separated. Many hairstreaks have fake antennas and eyespots on the end of the wing and this is thought to confuse a predator. They often perch and nectar head down so that the fake "head" is pointing up.

Coral Hairstreak

This is another common hairstreak in the park, the Coral Hairstreak. Unlike the Gray hairstreak, it lacks tails at the end of the wings. It is most often seen nectaring for long periods of time on flowers. Like the Gray hairstreak, it is about the size of a nickel.

Red-banded Hairstreak

And here is our third common hairstreak in the Park, the Red-banded Hairstreak. Like the Coral and Gray Hairstreaks it is about the size of a nickel. It is most often seen quietly perching on vegetation or nectaring on the flowers, especially the pink sedums in the summer.

Common Buckeye

This next butterfly is the Common Buckeye. It is an immigrant into our area from the south and is often seen late in the summer. The buckeye commonly perches on the ground and if disturbed will often fly around a bit and then come back to the same spot.

Cabbage White

The next butterfly is the extremely common Cabbage white. It is by far the most common butterfly in the park and can be found from early spring to late fall. Sometimes dozens can be seen at one time. I've heard it called a white moth many times but its a butterfly. It was not found in the United States prior to about 1860 when it was accidentally introduced from Europe. Since then it has expanded across virtually all of North America and beyond. While many people consider is a pest, the sight of dozens of these butterflies flying around the park is always fun to watch.

Spring Azure (and Summer Azure)

When you see this wonderful little butterfly, you know that spring has finally arrived! It is the Spring azure. We also likely have another species at the park, the Summer azure, which looks nearly identical but flies much later in the summer. Until fairly recently, this butterfly was thought to be one or two species or possibly a few different subspecies, but advances in genetic research and painsteaking fieldwork on larval preferences and flight phenologies (when they fly), have teased out what appears to be at least a half dozen (or maybe even more) different species that all look alike but that fly at different times and have different host plants for the caterpillars. You will most often see this little butterfly flying fast and somewhat erratically across the field or exploring high up in the trees at the edge of the field. It rarely perches or takes nectar from the planted flowers. It should be easy to recognize though, as it is the only small whitish blue butterfly that will be flying in that manner at the park. Regardless, along with the mourning cloak, it is a true harbinger of spring and always a welcome site in April!

Eastern-Tailed Blue

Here is our other tiny little bluish butterfly, the Eastern-Tailed Blue. It is probably our smallest butterfly and is about the size of a dime, sometimes even smaller. It is quite common at the park but because it is so small and typically flies weakly along just a few inches above the ground, it can be difficult to find unless you look for it. But when you find it, what a joy! It is a beautiful little butterfly with grayish undersides and a steel gray on the uppersides of the wings.

Eastern Tiger Swallowtail

These next two photos are of our largest butterfly, the Eastern Tiger Swallowtail. (We have three species of swallowtails at the park, East Tiger, Spicebush and Black) Tiger swallowtails are as large as a child's hand. These butterflies are often seen flying high up in the canopy of the forest, flying rapidly across the park or lazily nectaring on the butterfly bushes. When they are nectaring, they can often be approached very closely. The left photo is the typical color phase, bright yellow with black stripes (aka...a Tiger). The one on the right is the much less common dark phase. If I had to guess, I'd say that the typical yellow phase outnumbers the dark phase by at least 100 to 1. As far as I know, the dark phase occurs only in females and intermediate color phases can also occur.

Spicebush Swallowtail

Here is another of our swallowtail butterflies, the Spicebush swallowtail. It is smaller than the Tiger swallowtail but not by much. It is more restricted to woodlands than the Tiger swallowtail, but wanders widely and is commonly found nectaring on the butterfly bushes at the park. It is a beautiful butterfly.

Here is a photo of the undersides of the Spicebush swallowtail. It can be distinguished from the very similar Black swallowtail by the lack of an extra orange spot on the wing.

Here is a side by side comparison of the very similar black color phase of the female Tiger Swallowtail on the left and the Spicebush Swallowtail on the right. If you closely compare the orange markings on the wings you will see the differences. Note that the Tiger Swallowtail has crescent-shaped orange markings along the outer edge of the wing and the Spicebush Swallowtail has grayish blue ones. Also note the large orange spot at the upper edge of the hind wing in the Spicebush Swallowtail that is lacking in the Tiger Swallowtail.

I think this photo just screams "ain't nature incredible!" It is a Spicebush Swallowtail caterpillar. Note that the fake eyes are not on the head but on the abdomen of the caterpillar. As the caterpillar is totally harmless, the fake eyes make it look like a snake or at least not a caterpillar and much more aggressive then then it really is. When disturbed, it will rear the front of the body up toward an attacker and those prominent eyes will hopefully be "scary" enough to startle and scare off whatever is looking to eat it.

Black Swallowtail

The third species of swallowtail we have at the park is the Black Swallowtail. It is probably slightly less common then the Spicebush swallowtail, which is a bit odd because it is a meadow butterfly and typically found elsewhere in fields and open areas. In fact, at the nearby Community Garden it is often quite common laying its eggs on gardeners dill, carrot and parsley plants.

Here is a pretty awful photo of the male Black Swallowtail. The female lacks all the yellow and looks a lot more like the Spicebush swallowtail.

Photo Tip: This photo is a perfect example of what not to do when taking butterfly photos. Try to have the butterfly relatively straight on to the camera and perched as flat as possible. This butterfly is angled slightly which skews the wing shape. It is also not flat causing parts of the wing to be in focus and other parts out of focus. Also, avoid shadows that might cover part of the butterfly such as the big dark band across the right wing in this one. It is also missing both tails. Look for butterflies that are in good shape. And finally, try to note the background behind the butterfly. Avoid busy or irregular colors that detract from the butterfly such as in this photo. Look at the white line leading to the left wing from something in the background. Try to avoid these distractions.Otherwise if its digital shoot away! Out of every ten shots, one will probably be good.

Here is a photo of the Black Swallowtail caterpillar feeding on dill at the community garden. Whenever you see bright colors like this on a caterpillar, they are advertising a warning. Typically, in caterpillars that means a bad taste and various poisons generally from sequestering these compounds from the plants they feed on. The Black Swallowtail caterpillar goes a step further, having a cool forked fleshy organ called an osmeterium that is protruded from the head and that emits a really awful smelling odor. It is harmless to us, so if you find this caterpillar, give it a little soft push, get close and give it a whiff. You will see why a predator might choose to leave it alone.

Monarch and Viceroy

These next two photos are of the Monarch (left) and the Viceroy (right). They are the poster children for mimicry in the northeast and represent an example of Müllerian mimicry. This type of mimicry describes a situation where two or more species have very similar warning or aposematic signals and both share genuine anti-predator attributes (e.g. being unpalatable - they taste bad). Since both look similar and taste bad, they both get the benefit of protection from predators that may have encountered only one or the other of the butterflies. Note that the hindwing of the Viceroy has triangular tear marks that may be from the beak of a bird. Although both butterflies look similar, look for the heavy black band that runs horizontally across the hind wings of the Viceroy as a good field mark to separate them. At the Park, Monarchs are much more common then the Viceroy. Each year we see a few Viceroys, and I suspect they are originating from the many willow shrubs (a caterpillar food plant) found along Ireland's Brook behind the Summerhill and Fox Meadow townhouses. The monarch is a male. They are easily distinguished from the females by the dark oval marks on the hindwing veins closest to the body. These are scent glands that release pheromones during courtship.


Monarchs undertake an incredible migration from North America to the mountains of Mexico near Mexico City each fall. If you dont know about this migration, visit Monarch Watch ( and be amazed! It is one of the great biological migrations and one that in New Jersey we are lucky to be a part of. East Brunswick, New Jersey is right on the flight path of the fall migration and the monarch butterflies we see if September and October (and occassionally even early November) are all in transit on an incredible 3,000 mile flight south to Mexico (of course they dont all make it). We can assist the migrating monarchs by providing nectar sources like the many butterfly bushes at the Butterfly Park to help them gain essential nutrients for the long migration. Anyone can also participate in a long-term ongoing Citizen Science project begun in the 1930's to help understand the migration by tagging monarchs. When a tagged butterfly is found either in Mexico or somewhere along the migration route the details are entered into a huge database and scientists can use the information to help understand the migratory pathways. The details on how this works, and where to purchase tags are available on the Monarch Watch website. The photo above is a tagged monarch found this past summer at the Butterfly Park. The information from the tag was emailed to the scientists at Monarch Watch. Please let us know if you find any tagged monarchs at the Butterfly Park or elsewhere in East Brunswick.

The monarch caterpillar is equally fascinating. Like the black swallowtail caterpillar it sports bright in your face warning colors advertising its presence and making it clear to potential predators that it does not taste good and is poisonous. The caterpillars in this photo are on common milkweed, and this is the only plant they feed on at the park. If you have ever broken a leaf of milkweed, you know that it has a white milky sticky sap. This sap and the entire plant contain powerful poisons that are transferred to the caterpillar as it eats the leaves. The caterpillars are making it clear that they are poisonous. But these caterpillars also use another technique to hopefully avoid predators. They feature fake antennas on both ends of the body. It is believed that this may confuse a predator in some way. Look for monarch caterpillars at the park in the large milkweed stand that is growing near the bed along the main trail.

Great Spangled Fritillary

Along with the Monarch and Viceroy, we have one other large orange butterfly at the park (we have quite a few small ones too), the Great Spangled Fritillary. This is a beautiful butterfly with burnt orange colors and white spots that shine like silver in the right light. It is about the size of a silver dollar. It is a very strong flier and at times can be quite skittish and difficult to approach. But at other times it will quietly nectar for long periods on the butterfly bush and other flowers allowing a very close approach. Just move slowly and you may be rewarded with a close-up look at one of our most beautiful butterflies. Like all fritillaries, the Great spangled caterpillars feed on violets and typically in moist or wet habitats. The butterfly park does not have the correct habitats or violets for the caterpillar so the adults we see are just passing through. Fortunately, our little park can offer a respite as they fly around searching for suitable breeding habitats.

Mourning Cloak

This next butterfly should probably have been first in the field guide regardless of taxanomic order. It is the Mourning Cloak and is our first butterfly to appear in the spring. The Mourning cloak is often seen on warm days as early as March sometimes even when there is still a little snow on the ground. The reason it can fly so early is because it overwinters as an adult, in some protected place, like beneath bark or in a tree cavity. The butterfly has glycol in its blood which is essentially an anti-freeze preventing the water in the blood from crystallizing. On warm spring days it will emerge from its winter roost and fly about for a few hours often settling in small sunny spots on a trail. As the day gets cold it will reenter a secluded hiding spot waiting until the next warm day to fly around again. It has a habit when disturbed of flying around and then landing right back in the same little sunny warm spot. As you can see from the photos it is exceptionally well camouflaged for a butterfly that flies early in the spring (primarily, there is also a smaller brood later in the summer) with wings that look just like a dead leaf or a piece of bark.

Little Wood Satyr

In late May or early June at the Butterfly Park this really cool butterfly can be found, but only for a few weeks and only in limited numbers. It is the Little Wood Satyr. The park supports a small population and they can be seen flying low through the meadow and along the woodland edge. They don't perch or nectar at flowers very frequently but fly slowly enough that they can be followed fairly easily if you don't mind trudging through brambles and poison ivy. But once you get a good look at this quarter-sized butterfly, the scratches and itching will be worth the effort!

Red Admiral

The beautiful Red Admiral is one of the more common butterflies at the Park. It is about the size of a half dollar. It can be quite pugnacious darting out and toward a passerby from a favorite perch.Sometimes it will even land right on the person. When it is disturbed, it will fly about in a seemingly wild and erratic way only to resettle at the same spot over and over again. It gets its common name from the red and blue markings on the wing that are supposed to resemble the epaulets of a military uniform.

Quiz time: How many legs do butterflies have? As with all insects, the number is 6. But take a look at the Little Wood Satyr and the Red Admiral above. Look at the Comma, the Monarch, the Viceroy, the Mourning Cloak and the Great Spangled Fritillary. Aren't there only 4 legs on these butterflies? All of these butterflies, and a few others at the Park belong to a large group known as the Nymphalidae, or Brush-footed butterflies. These butterflies have three pairs of legs, but the front pair is highly reduced and no longer utilized for walking. Through evolutionary time, these legs have migrated toward the front of the head and now serve as sensory organs. They are covered with brush-like sensors, which is where the term "Brush-footed" comes from. You can see them in the photos as the somewhat pointy and fuzzy "nose" at the front of the head.

American Lady and Painted Lady

We have two species of Lady's at the Park. The very common American Lady and the less common Painted Lady.They can be distinguished by the number of spots on the underside of the hind wing. The American Lady has two big prominent spots and the Painted Lady has 5 smaller ones. The first photo is the American Lady and the second the Painted Lady.

This is the American Lady with the wings open. It looks very similar to the Painted Lady, but the American Lady has slightly different black markings and four small, but distinct blue spots on the wing. For beginners, the best way to identify these two species is to try and get a good look at the underside of the wings and see if there are two or four eye spots.
Pearl Crescent

This small orange butterfly is the Pearl Crescent and is very common at the park. It is about the size of a quarter. Despite its size, it is a suprisingly fast and agile flier, especially when it is disturbed. However, much of the time it will be flying lazily around and nectaring quietly at the low growing flowers.

Variegated Fritillary

This next orange butterfly is the Variegated Fritillary. It is a lazy and relatively weak flier and typically alights on the ground or on low vegetation. When it is disturbed, it will often fly a short distance and land again. It is a southerly species that immigrates into the northeast during the summer and is therefore most commonly seen at the Park from July through October. It is fairly uncommon with only a few typically seen in a given year.

Clouded Sulphur, Orange Sulphur and Cloudless Sulphur

These next butterflies belong to a very large family known as the sulphurs due to their yellow color. At the Butterfly Park we have two common species and one that has been seen only twice. The two common species are the Clouded Sulphur and the Orange Sulphur. The uncommon one, is the Cloudless Sulphur. The Clouded and Orange Sulphurs often hybridize making definitive identifications difficult. To further complicate matters, there is a white color phase of females and these are virtually indistinguishable in the field. In general, (with the exception of the white phase) sulphurs with distinctive orange (the orange is on the inside of the wings) are considered Orange Sulphurs and those lacking orange, Clouded Sulphurs. Generally, the orange can be seen even when the wings are closed. Both the orange and clouded sulphurs are about the size of a quarter. The photo below maybe a Clouded Sulphur due to the apparent the lack of evident orange on the wings.

Here are photos of a typical Orange Sulphur showing the abundant orange coloration and a typical white phase sulphur.

The Cloudless Sulphur is considerably larger then the Clouded and Orange sulphurs, about the size of a half dollar. While the two common sulphurs frequently perch and take nectar from flowers, the Cloudless is most often seen in New Jersey as a fast flying large yellow butterfly. It is a late summer immigrant into our state from more southern areas. The photo below is a specimen collected at the Butterfly Park on September 18, 2009. It is only the second seen at the park.

Red-Spotted Purple

The Red-spotted Purple gets its name from the underside of the wings, that lo and behold are purple with red spots! At the park, this beautiful butterfly is most commonly seen in late summer. It is often found nectaring on rotting fruit.

Hackberry Emperor

This next butterfly, the Hackberry Emperor, is host specific, meaning that it's caterpillars only feed on a particular plant. In this case, it is the hackberry tree, where it derives it's common name from. Because the butterfly caterpillars only feed on hackberry leaves, the butterfly is typically found near the trees. It is most commonly seen on the tree trunk, often perched head down, but will also land on people and take salts from perspiration. This butterfly is very uncommon at the park, seen once a year or so. The only place it has been found so far is along the woodland trail near Rues Lane. Oddly, there aren't any hackberry trees there. The closest one is at the entrance to the Butterfly Park on the left side as you enter from Great Oak Park just before the shed. It is worth searching around this tree for this interesting butterfly. Hackberry is easy to identify because the bark has lots of small wart-like bumps.

Common Wood Nymph

The Common Wood Nymph is now very uncommon at the park and may not even occur there anymore. It has been a few years since it was last seen. Before and right after the park opened it occurred in small numbers but was seen every year. It is possible that the management of the fields and annual cutting modified the habitat and made it inappropriate for the wood nymph. Please report any sightings of this butterfly.


So what are skippers? These are the small typically brownish or orangish butterflies that often whiz around the flowers. This behavior is the reason for the common name of "skipper". Scientifically, they are closely related to our "true" butterflies but are separated by some very technical morphological characteristics. In particular, they typically have relatively stout and large (fat) bodies, small angular wings and a thin extension at the tip of the antenna known as an apiculus or antennal club. We have two general types of skippers, the spread-winged skippers and the folded-winged skippers. As their names suggest, the spread-winged skippers generally land with the wings out flat while the fold-winged skippers land with the wings either completely closed over the back or with the hind wings more or less open and the forewings closed. In many species, markings on the open hindwings are the key to identification. Wade and Sharon Wander, two of the best butterfliers in the state have prepared a photo-based key to these markings that is an absolute must for anyone wanting to seriously start to learn the skippers. Although many skippers are relatively easy to identify, others can be incredibly difficult. Some groups of species are so similar looking that positive identification may not be possible without dissection of the genitilia or even genetic analysis. Sometimes habitat or season can also help distinguish between similar looking species.

Spread-winged skippers

We likely have somewhere between 3 and 5 species of spread-winged skippers at the park; Juvenal's duskywing, Horace's duskywing, Wild Indigo duskywing and the Common sootywing. We have also had the Common Checkered skipper once, the first year after the park was created but not again since then.

Juvenal's and Horace's Duskywings

These two relatively large spread-winged skippers are visually very difficult to tell part and the identification is based on subtle differences in wing markings. Juvenal's tends to fly earlier in the spring and Horace's in the summer. Juvenal's is typically much more common at the park. Wing markings that can be used to separate these two species are the two pale subapical spots on the hindwing in Juvenal's that are almost always absent in Horace's. Other subtle wing markings can be used but those are beyond the realm of this field guide. Here are two photos of what we suspect to be Juvenal's duskywing. One is very brown, the other very dark showing how there can be significant variability even within a species.

Here is a photo of what we suspect to be Horace's duskywing.

Wild Indigo Duskywing

This next photo is probably a slightly worn Wild Indigo duskywing.

The next group of skippers are all folded-wing skippers. We only have photos of some of these found in the park but will update the guide as the summer progresses. Please send us photos of any skippers found at the park that aren't in the guide. A list of the fold-winged skippers found in the Butterfly Park include:

Tawny-edged, Peck's, Northern broken dash, Sachem, Delaware, Hobomok, Zabulon, Broad-winged.

Broad-winged Skipper

A large skipper with caterpillars that feed on common reed.

Peck's Skipper

A common and relatively easy to identify skipper with distinctive markings.

Delaware Skipper

An unmarked bright orange skipper typically easily identified by the distinctive bright orange color that is almost glowing.

Tawny-edged Skipper

The tawny-edged is fairly easy to identify by the orange upper portion of the wing on an otherwise dull brown body.

Silver-spotted skipper

The largest and most distinctive skipper in the park. It is often quite abundant. It can be easily identified by the large white (or silver) spot on the wing, hence the common name.


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