Black Swallowtail

[gwang]

Hi y'all,
Just curious how far black swallowtail males (if there is in fact a
diff. between the sexes) usually fly from their eclosion site.  I've
seen a few around my area, but only males, and despite my efforts, I've
been unable to find the host plant/larva for this species.
Does anyone know the rough area in which I should search for the larvae?
Perhaps a few hundred metres or so around the sighted swallowtail?
 
Thx in advance,
Xi Wang