An Increase of Large Orange Sulphurs in South Jersey

In the past two years, Large Orange Sulphurs have been spotted in Cape May and Cumberland Counties on 5 different occasions between three observers. Traditionally a south Florida and neotropical species, could climate change be encouraging a northbound range expansion, or increased vagrancy?

Large Orange Sulphur (Phoebis agarithe) is one of the most perplexing butterflies in the east. At least on the eastern seaboard, Large Orange Sulphurs only occur in south/southeastern Florida. They're dominantly a subtropical/neotropical species, with the thick of their range in the US being between southern California and Texas, then through Central America, the Caribbean, South America, and even out in the chain of pacific islands that build up Hawaii.  For whatever reason, there is a gap in range where the species does not occur, between the western edges of Louisiana, all the way to central/south Florida. However, the species has a long history of showing up far out of range in the United States. 

Of these sites, they have most consistently expanded northward from Texas, showing up in places like Colorado, Missouri, and Kansas. From there, there have been sightings in random pockets in the far north of Wisconsin and twice in South Dakota. Heading east, they have been found in a diagonal line through Arkansas, Kentucky, and out towards Maryland; and then another diagonal line across upstate New York, New Hampshire, and Maine. There is also a historical record for central NJ and again more recently in 2022, when two showed up at Cape May Point in September. The reason why is largely based on assumption. Since at least the mid 1990s, if not earlier, Large Orange Sulphurs have been recorded in the northeast on more than one occasion. Vagrancy in butterflies, especially with southern species, is typically a fall occurrence. There are already several southern species of pierids (including sulphurs) and skippers that make annual northerly migrations and at times, even with irruption. The species, as with other rare southern butterflies, should always be on the radar during the fall. However, there are historical records of Large Orange Sulphur as far north as New York during the month of June. It might very well be an expected “spring” vagrancy time for them to show up in odd places. 

Large Orange Sulphurs have a wide array of recorded host plants in the United States. This includes ebony, feather bush, and blackbrush acacia in Texas and blackbeads (Pithecellobium), Inga, and wild tamarindin Florida and California, just to name a few. Orange Barred Sulphur, which has similar, but less consistent vagrancy across the US, which has shown up in North Carolina and Indiana, and with historical records as far north as New York, Michigan, and Minnesota, hosts on more common northern species like sennas, cassias, and others that people like to put in their gardens. Neither species really has the chance to colonize in the north because they don’t have the tolerance for overwintering in the northeastern climate. However, if host plants were found, it wouldn’t stop them from laying eggs and from caterpillars feeding on hosts. Maybe in a decade, or two it will be warm enough during the winter for them to colonize, but for now, we are still in a much different time period than the late 1900s. Shifting thoughts to southern New Jersey and even more specifically, Cape May County, climate change has had fast effects on the region. South Jersey, in other words, is the new Florida. In 2020, the first breeding record of White Ibis occurred in the state at the Ocean City Welcome Center. This past spring in 2023, over 400 pairs were found in this site alone. Several sightings of Mississippi Kites, Brown Boobies, Painted Buntings, Gray Kingbirds, etc. have been rocking the Cape May area over this same three year stretch. These are all southern birds that are becoming more and more common each year. On top of this, the first Ruby-throated Hummingbirds in state history have been successfully overwintering in Cape May. Numbers of this have been increasing more and more. Eufala Skipper was seen in November of 2021 in Cape May and the first photographed record of Large Orange Sulphur took place in September of 2022 at Cape May Point. Three Sleepy Oranges were found this past April, 2023, as adults in winter form, which would signify the first time ever that an adult Sleepy Orange overwintered in NJ. Things are changing. Climate change is having a quick, dramatic effect on wildlife in the south and we’re seeing these species expanding their ranges little by little. 

On June 5th, 2023, I had a Large Orange Sulphur fly through my yard. On June 9th, I saw one fly across the road on 83 by Beaver Swamp WMA. On June 11th, Jack Miller and I had one fly across a field in Cedarville, Cumberland County. The key thing to understand is that Large Orange Sulphurs, even on the wing, are not hard to identify in NJ. The reason why is due to the simple process of elimination. This goes for both color and behavior. Anything of that size and deep orange is not going to be a weird Cloudless. Even when considering Orange Barred, Orange Barred has a more contrasted color with the forewings being deep sunset orange and the hindwings being a pure yellow. This can be noticeable in flight. Large Orange has very consistent, evenly blended orange across the whole butterfly. Cloudless Sulphurs become paler as they lose scales and even sometimes appear green, as their wing membrane is reflective of the color. Large Orange Sulphurs can be pale white (alba females), but will have cloudy gray edging on their forewings. The size and blurry gray in the white should make it stand out. The most important factor when watching a Large Orange Sulphur fly, is to notice the speed and altitude of their flight. They are very fast, direct, and usually fly mid-tree level (10-30ft). In circumstances where Orange Sulphurs are present, they act and fly nothing like them. Orange Sulphurs are always much lower to the ground and can be described as “happily” fluttering about habitats, where Large Orange is noticeably in a rush and could even at times, be described as “frantic”. Large Orange Sulphurs fly very similar to Cloudless Sulphurs, but might even be faster and on average, fly at larger heights more consistently than Cloudless (likely because they host mostly on trees and may be seeking egg laying sites and nectar in the canopy). 

Now that the natural history of the species and the general gist is out there, let’s run it back for a moment to the mentioned range “gap” between Texas and Florida. This gap makes the somewhat isolated Florida population a unique case. It is clear that the question is no longer, could, or do Large Orange Sulphurs show up in New Jersey, as with increasing global temperatures, I would expect the species to start becoming annual in the next couple years, if they aren’t already. My question now is where are they coming from? If Large Orange Sulphurs in the west are expanding north and east from Texas and flooding across the bulk of Oklahoma, Missouri, Colorado, Louisiana, etc., with crazy vagrancy nearly to Canada, then why aren’t the Florida butterflies doing the same? There should be far more than two, or three reports in the Carolinas and they should regularly be seen (as rarities) all along the coast from Georgia to at least the Chesapeake Bay (based off of the western LOS behaviors). However, there just isn’t. The ones that showed up in North Carolina, I would no doubt expect that they came from Florida. Even the recent NJ report from 2022 in Cape May was right at the time that Hurricane Ian annihilated Florida, which probably influenced vagrancy for the species. Yet, butterflies in NY, NH, and ME have me guessing. My hypothesis is that sulphurs from the west get directed north against the mountains, getting scooped up and bent north from the Smokies and pushed toward New England and the mid-Atlantic by the continuing north along Appalachia. That’s why they’re showing up in places like upstate New York and in other New England states. Now, this is where things get interesting to me. There are records for Maryland and northern New Jersey. There is a gap in the mountains right across in western Maryland and again coming back south in New York below Albany. This could mean that Maryland, or NY/NJ records could be individuals that came from the west - if they are indeed being directed by the mountains. In my eyes, Maryland records could be from either direction - from the south, or west. If that is the case, it is possible Large Orange Sulphurs showing up in NJ could be from the west, or south. However, I would expect due to the nature of northbound migrations from the south during the fall, that it is probably more likely that autumn sightings are from Florida, but yet again, who knows?

The question lies in just how conservative are these Florida bugs? Could it be that spring records are more consistently from the west and that fall records are from the south? Could it be both? Could western butterflies really make it that far? Sightings data showing western behavior would certainly make it seem so. Plus, we know that Painted Ladies make dispersal movements from the deserts of Texas during the fall and are found all the way across the country into the northeast, making migrations up the coast. Is it possible that Large Orange Sulphurs could do the same? If anything, the question on people's minds should be Large Orange, or Orange Barred? In recent years, sightings data has shown that Large Orange has been way more consistent in showing up in new regions. There are a lot of “historical” records of Orange Barred, but few confirmed recent reports. I wonder if some, if not the majority of historical records, were actually Large Orange. Large Orange Sulphur is a species that people should keep in mind while butterflying. Although they hardly stop, the species loves nectaring from tubular red flowers. In Florida, their favorite nectar source is firebush (particularly during the spring/early summer). However, they can be attracted pretty easily to any red, or pink bunches of flowers. It is a butterfly that could easily be missed due to its flighty nature, which makes for quick and far in between encounters. Perhaps if more people have them on their radar, we’ll find out that they’re more annual than we ever thought - especially in today’s world. 

- by Jack McDonough

Coordinator

NABA South Jersey Chapter