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Title: Information Sheet, Rock Creek Park Arthropods

Information Sheet, Rock Creek Park Arthropods. A Short Virtual Tour of Rock Creek Park in the Vicinity of the Nature Center.

Rock Creek Park is a national park in Washington, D.C. It covers 1,754 acres (710 hectares) and extends about 4 miles, generally being about 1 mile wide (Fales 1987). Rock Creek flows through the entire Park which includes part of the Piedmont Province, the Fall Line, and the Coastal Plain Province. Mature second-growth, primarily angiospermous forest covers most of the Park. Mowed lawns, restored meadows, the Creek, buildings, and a golf course comprise the rest of the Park.

What arthropods can you see in Rock Creek Park on a hot, sunny afternoon in June?

From about 1 through 3:30 p.m., on the hot, sunny, code-orange day of 27 June 2003, I took an arthropod adventure hike in Rock Creek Park, Washington, D.C. Four GU-NPS Interns (Bao, Christi, Matt, and Toan) went on the first half of the hike.

The Common Milkweeds (Asclepias syriaca)

There is a small patch of Common Milkweeds* in front of the Rock Creek Nature Center, and a larger patch behind it. During a hot, sunny spell today, many butterflies visited these flowers which were in full bloom. The butterflies were female and male Great Spangled Fritillaries* (Speyeria cybele) and Tiger Swallowtails* (Pterourus glaucus) and a Silver-spotted Skipper* (Epargyreus clarus). One Fuscate Paper Wasp (Polistes fuscatus), many small carpenter bees (Ceratina sp.), one worker Honey Bee* (Apis mellifera), several female Large Carpenter Bees* (Xylocopa virginica), and many worker Wandering Bumble Bees* (Bombus vagans) drank nectar from these flowers. One large black-and-yellow digger bee* (Andrena) sp., hung dead from a Milkweed flower. After I pulled this bee from the flower, I found that she had three pollen sacs (pollinia) attached to her legs. Evidently, she could not pull loose from the flower and died trying to do so. Common Milkweeds sometimes kill Honey Bees (which are about twice as large as this digger bee) because the Honey Bees cannot pull out the pollinia and leave the plant. A small, worn male Great Spangled Fritillary courted a large new female that rested on a Milkweed inflorescence. Male Tiger Swallowtails also courted conspecific females on the flowers. All of the females were the black-and-yellow form, not the dark form. One Milkweed Beetle (Tetraopes tetraophthalmus) rested on a leaf and an azure butterfly, possibly a Spring Azure* (Celastrina ladon) flew in the area.

Forest Openings

There was a small forest opening with alien Canada Thistles (Cirsium arvense) in flower. One alien Imported Cabbage Butterfly* (Pieris rapae) took nectar from that species. Another opening had a flowering patch of Indian Hemp* (Apocynum cannabinum), which had no nectar-collecting insects.

The Pond

There is a small pond near the Nature Center. Duckweed (Lemna) covered most of its water. Eastern Yellowjacket* workers (Vespula maculifrons) landed on the duckweed and drank water. Those wasps usually do not sting people when they are not protecting their nests. A waterstrider* (Gerridae) ran over the duckweed. No odonates flew around the pond today.

Sooty Mold

In spring and early summer 2003, aphids* in Tuliptrees* produced copious amounts of honeydew. Their honeydew covered leaves of many species, and dark sooty mold grew on leaves using the honeydew as a food source. In 2003, there was little rain in late May and June that would wash off the honeydew, and it covered leaves in many parts of the Washington, D.C,, Area more than any other year since 1986.

The Path to Fort DeRussy

On the way to the Fort, from the Nature Center, I crossed loud, busy Military Road. On the south side of this road is a rank growth of Asiatic Bittersweet* (Celastrus orbiculatus) with vines climbing on each other into the air. A large wolf spider* (Lycosidae) rested on a group of Asiatic Bittersweet leaves which were tied together with silk and harbored about 100 yellow-brown spiderlings. The larger spider might have been the spiderlings’ mother. This path goes through dense angiospermous forest. As I hiked on it, the sky became overcast. A large black carpenter ant* (Campanotus sp.) and a brilliant green Six-spotted Tiger Beetle* (Cicindella sexagutata) scurried on the ground. One tree had many oyster mushrooms, most were on the east side of it trunk and old and dry. One group of fresh oyster mushrooms grew on the west side of the tree. A beetle, black carpenter ant, and several ichneumonoid wasps* crawled on these mushrooms. As I hiked in the Park and saw the ants, I thought about the great biologist Edward O. Wilson, a renowned ant and biodiversity specialist. When he was a boy he visited the Park. The ants that he found in a log inspired his life’s work. Rock Creek Park is certainly a special place.

Butterflies in Rock Creek Park

John Fales (1987) reported that of the 97 butterfly species known from Washington, D.C., butterfly hunters found 58 species in Rock Creek Park. Pat Durkin (2003) surveyed butterflies in the Park in 2002. She found 24 species, including two species that John Fales did not report in his lists for the Park.

To see many other organisms that I saw at Rock Creek Park on 27 June 2003, please use the keyword RCP030627.

To see other BDWA pages on forts of the Washington, D.C., Area, please go to BDWA’s homepage and enter the term “fortdc.”

* = an organism with one or more images on this Website. Some of the images are from Rock Creek Park.

E. M. Barrows (2003)


Durkin, P. 2003. 2002 Survey of Butterflies of Rock Creek National Park (21 March 2003). Unpublished report.

Fales, J. H. 1987. The Butterflies of Rock Creek Park, Washington, D.C. The Maryland Naturalist 31: 5–24.

Please, click on images to enlarge them.

Figure 1. An entrance of Rock Creek Park.

Figures 2–3. Early succession in a new meadow.

Figure 4. A new meadow.

Figure 5. Speyeria cybele (Great Spangled Fritillary, Nymphalidae) on Asclepias syriaca (Common Milkweed, Apocynaceae).

Figures 6–7. Solanum carolinense (Horse Nettle) (Solanaceae) surrounded by grass.

Figures 8–10. A temporary pond.

Figures 11–12. Asclepias syriaca (Common Milkweed) (Apocynaceae).

Figures 13–14. A dead Andrena bee that might have died because she was stuck to a Common Milkweed flower by its pollinia. Note orange pollinia on her legs.

Figure 15. A new female Pterourus glaucus (Tiger Swallowtail, Papilionidae) of the yellow form.

Figures 16–18. Near Fort De Russy, a Civil War fort in Rock Creek Park.

Figures 19–20. A fungus.

Figures 21–22. Hamamelis virginiana (Common Witch-hazel, Hamamelidaceae).

Figure 23. Part of a new meadow.

Figure 24. An igneous rock in the forest.

Figure 25. Part of the stream near Fort De Russy.

Figures 26–27. Part of the stream near Fort De Russy.

Figure 28. Sooty Mold growing on Lindera benzoin (Spicebush, Lauraceae) leaves.

Figures 29–30. Part of the stream near Fort De Russy.

Figures 31–32. Rubus sp. (Dewberry, Rosaceae) fruit.

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