Two-tailed Swallowtail Papilio multicaudata:
Wing span: 3 1/2 - 5 inches ( 9 - 12.7 cm )
Upper surface of male forewing with narrow black stripes. Each hindwing has 2 tails hence it's commen name.
Western NA south from British Comlumbia, east to central Nebraska and central Texas, south through Mexico.
Foothill slopes and canyons, moist valleys, streamsides, woodlands, parks etc.
The rest of the info can be found at www.bugguide.net/node/view/2391