Larval Hostplant List for Butterflies of the Washington, DC
Area has that listed as a host. This is a good list of host plants and goes far beyond the DC area.

I saw some one post a picture where the Black Swallowtails had used Citrus, too.

I really recommend getting "The Butterflies of North America, A Natural History and Field Guide" by Dr. James A. Scott on Multimedia CD ROM. I've copied a list of host plants from it below. You can get used copies on Amazon, that are very inexpensive.

"Habitat Subtropical to lower Canadian Zone woods, mountains, and suburbs; mostly Lower Sonoran Zone desert for ssp. coloro. Hostplants (a or no letter, ssp. asterias; c, ssp. coloro; k, ssp. kahli; j, "joanae") herb Umbelliferae: Angelica ampla, atropurpurea, venenosa, Anethum graveolens, Apium graveolens, Conium maculatum, Daucus pusillus, carota (ack) (and var. sativus (a)), Cryptotaenia canadensis, Foeniculum vulgare (ac), Harbouria trachypleura, Heracleum lanatum, sp.(k) (rarely used), Levisticum officinale, Ligusticum scothicum, Berula erecta, Osmorhiza longistylis, Oxypolis canbyi, Pastinaca sativa (ak), Petroselinum crispum (ack), Ptilimnium capillaceum, Carum carvi, Cicuta maculata, bulbifera, douglasii, Sium suave, Spermolepis divaricata, Taenidia integerrima (aj), Thaspium barbinode (aj), Zizia aurea (kj), aptera (k) (main host of kahli and its form comstocki), Cymopterus panamintensis var. acutifolius (c) (occasionally), Tauschia parishii (c), arguta (c) (Hydrocotyle is doubtful because lab larvae refused H. umbellata and americana); herb and shrub Rutaceae: Thamnosma texana (a), montana (c) (usual host), Ruta graveolens (ac) (Penn., Ill., Ga., Mo., Tex., Mass., Calif.), Dictamnus albus. Larvae are attracted to the Umbelliferae oils methyl chavicol, anethole, anisic aldehyde, anisic acid, carvone, coriandrol, and sedanolid, and to the Rutaceae oil methyl-nonyl-ketone (V. Dethier); lab larvae will eat even Cosmos and Solidago (Compositae), which have similar oils. Umbelliferae plants produce certain chemicals, linear furanocoumarins (psoralins), to repel insects that try to eat them. Larvae are resistant to psoralins that kill other insects because the intestine and body rapidly detoxify and eliminate them, but angular furanocoumarins reduce larval growth (M. Berenbaum, P. Feeny, G. Ivie, and others); the psoralins discourage other insects, and some Umbelliferae species now produce the angular ones to discourage polyxenes. The psoralins actually increase the growth rate and decrease the mortality of polyxenes eating them (Berenbaum). J. Erickson and J. Scriber raised polyxenes on many other lab Umbelliferae; larvae grew 25 percent faster on cultivated than on wild Umbelliferae, probably because some insect-repelling chemicals, such as the angular ones, have been bred out of the cultivated species to make them more edible for people. P. polyxenes can survive on Magnolia leaves in the lab. Ssp. coloro larvae refuse Citrus, which P. zelicaon larvae eat."

Here is a link that might be useful: Larval Hostplant List for Butterflies of the Washington, DC Area and Beyond