A Day of Butterflies

Today was all about butterflies. Early this morning, my family and I left for Fort Indiantown Gap (FIG), which is located in Lebanon County, PA. This site is an active military training location and is the only location in the eastern United States with a remaining population of the Regal Fritillary butterfly. Every year, the researchers from FIG lead butterfly tours that showcase the rare and beautiful fritillary. Here is a photo essay about my day at FIG as well as my butterfly findings in my yard this afternoon.

Soon after arriving at the first location for the Regal Fritillary, a few of the researchers caught a few butterflies to show the large group. They explained and showed the differences between the males and females, as well as the distinctions between the other fritillaries in the region: the Great Spangled and the Aphrodite. This is a female Regal.

A few of the butterfly watchers in the grassland at Fort Indiantown Gap. The grassland was originally created by military activity, allowing a perfect place for the Regal's larval foodplant, Arrowleaf Violet (Viola sagittata), to grow. Now, much of the Regal Fritillary habitat at Fort Indiantown Gap is maintained by controlled burns and mowing.

Although the Arrowleaf Violet is a necessary plant for the success of the Regal Fritillary, nectar plants such as this Butterfly Milkweed (Asclepias tuberosa) are equally important. The adult butterflies cannot survive without nectar plants such as milkweeds and thistles.

Here is a male Regal Fritillary chasing a female. The butterfly on the right is the male, which can be determined by the row of orange spots on the hindwing. The female has a row of white spots (visible on the first photo).

Many of the Regals rarely landed, which made them difficult to photograph. This individual sat to nectar for a few seconds and allowed me to take photo.

The Regal Fritillary is the main attraction at FIG, but many other butterfly species (over 80) have also been recorded in the various habitats included within FIG. American Coppers, like the one pictured above, were fairly common along the paths in the grassland today.

Another fairly common species in the grassland is the Aphrodite Fritillary. This species resembles a small Regal Fritillary without the black on the hindwing.

One of my favorite butterflies of the trip was this Zebra Swallowtail that nectared on Butterfly Milkweed along the border between the grassland and the forest. The zebra-like bands of black and white, along with the red line and long "tails", make this an unmistakable butterfly of "southern" forests in the eastern United States.

As well as seeing good numbers of butterflies at FIG, we also saw quite a few dragonflies. This Halloween Pennant perched on this twig and occasionally flew off to catch small insects. Other dragonflies that we saw flying around the grasslands included Common Green Darner, Widow Skimmer, Twelve-spotted Skimmer, and Carolina Saddlebags.

After the trip to FIG, I did some more butterflying in the milkweed patch in the field across from my house. The first species I found was this Black Swallowtail nectaring on Common Milkweed (Asclepias syriaca). At first glance, this species looks similar to the Spicebush Swallowtail, but the complete orange spot-band identifies this as a Black.

The most abundant butterfly species in the patch was Little Glassywing. I did a quick count of these guys on the milkweed flowers and counted about 150 individuals.

At times, the Little Glassywing filled the flower heads of the Common Milkweed. Mixed in with the glassywings were other skippers such as Silver-spotted, Dun, and Delaware Skippers, and Northern Broken-Dash.

Northern Broken-Dashes have just started to emerge here in southern Monroe County. The glassywings are at their peak right now, but in a few weeks, they will be mostly replaced by this species.


Other common species like this Eastern Tailed-Blue visited the milkweed flowers too. This tiny, blue butterfly is sometimes difficult to photograph, but this individual sat still long enough for me to get a good photo.


Since I began butterflying a little over a year ago, I have looked for Banded Hairstreaks in the yard. Last year, I managed to find several less-common hairstreak species, but not the "common" Banded. Earlier in June, I saw reports on the PALepsOdes list of Banded Hairstreaks visiting Indian-hemp and Common Milkweed flowers, so I diligently checked every flower I came across hoping for one. After a week or two, the posts stopped, and I figured I had again missed the Banded Hairstreaks. Then, about two days ago, I looked out to a Common Milkweed along the side of the house and saw a hairstreak! I rushed out, and sure enough, it was a Banded. I was extremely excited to finally find one in the yard. Then today, when I went to check the milkweed patch and found over a dozen Banded Hairstreaks, I was amazed. Not only were the hairstreaks in abundance, they were also very cooperative and provided great photo opportunities.


At times, the hairstreaks shared the flowers with other butterflies.

While looking for hairstreaks, I noticed one that looked a little bit different than the Bandeds. This one was larger, grayer, and had a very different pattern on the wings. From a distance, I thought it was a Gray Hairstreak, a common hairstreak in this area. As I got closer, I noticed that the white lines on the wing formed an "M" and there was a distinctive white dot close to the base of the wing. These characteristics identify this individual as a White M Hairstreak, one of the uncommon hairstreaks on the property.

While meandering through the milkweeds, I glanced over to an area with thistles and noticed an unusual-looking dark butterfly flying low in the grass. I was unfamiliar with this particular flight pattern and coloration, so I went over to get a better look. When the butterfly finally landed and opened its wings, it was clear that my mystery butterfly was a Baltimore Checkerspot. This incredibly beautiful species is one that I had never seen before, and never expected to find in the yard. I spent several minutes just enjoying this wonderful butterfly and the amazing patterns of black, orange, and white on the wings.

The Baltimore Checkerspot has my vote for the most strikingly-colored butterfly in the region. When the wings are closed, the patterns become even more interesting and detailed. This butterfly was an awesome way to end an exciting and butterfly-filled day!


This patch of Common Milkweed has been incredibly productive for butterflies this year. Every year it gets bigger, providing more nectar for the butterflies mentioned above, as well as hosting numerous other insect species. I strongly encourage everyone who has a garden to plant some milkweed, for it will provide food for an incredible array of native insects. Nectar-eating adults of the skippers and hairstreaks will be attracted to the large clusters of flowers and the larval stages of Monarchs and Milkweed Tussock Moths will benefit from eating the leaves.