Ask Mr. Smarty Plants

The Butterflies and Moths of North American website says that the flowers visited for nectar by the adult Danaus gilippus (Queen) include milkweeds and milkweed vine—these are also the larval hosts.  Other flowers listed by that website are  Phyla nodiflora (Texas frogfruit) [blooms May through October] and Bidens alba (Common beggarticks).  Bidens alba doesn't occur in Travis or Williamson Counties but Bidens laevis (Smooth beggartick) [blooms June through October] does grow in Travis County.   

As well as Conoclinium greggii (Gregg's mistflower) [blooms March through November], there is Conoclinium coelestinum (Blue mistflower) [blooms July through November] that butterflies love.  Both occur in Travis and Williamson Counties and attract the Queen and other butterflies.

Queen Elizabeth Botanic Park in the Cayman Islands reports that Queen butterflies visit Lantana sp. and Croton sp. In Travis and Williamson Counties these would be:

• Lantana urticoides (Texas lantana) blooms April through October.
• Croton alabamensis (Alabama croton) blooms February through April according to Alabama Plants.
• Croton capitatus (Hogwort) blooms July, August and September.
• Croton fruticulosus (Bush croton) blooms April and May.
• Croton glandulosus (Vente conmigo) blooms July through October.
• Croton lindheimerianus (Threeseed croton) blooms March through November.
• Croton monanthogynus (Prairie tea) blooms April through September.

Below are the native plants in the Family Asclepiadaceae (Milkweed Family) that occur in Travis and/or Williamson Counties:

• Asclepias asperula (Spider milkweed) blooms March through October. 
• Asclepias latifolia (Broadleaf milkweed) blooms July through October.
• Asclepias oenotheroides (Zizotes milkweed) blooms March through September.
• Asclepias texana (Texas milkweed) blooms May through September.
• Asclepias tuberosa (Butterflyweed) blooms May through September.
• Asclepias verticillata (Whorled milkweed) blooms May through September.
• Asclepias viridiflora (Green milkweed) blooms June through September.
• Asclepias viridis (Green antelopehorn) blooms April through September.
• Cynanchum barbigerum (Bearded swallow-wort) blooms March through July.
• Cynanchum laeve (Honeyvine ) blooms July through September according to Missouri Plants.
• Cynanchum racemosum (Talayote) bloomtime data is not available.
• Funastrum crispum (Wavy-leaf milkweed vine) blooms April through August according to Yavapai County Native & Naturalized Plants from Arizona.
• Matelea biflora (Purple milkweed vine) blooms March through June.
• Matelea edwardsensis (Plateau milkvine) blooms in April and May.
• Matelea gonocarpos (Anglepod) bloomtime given as mid-summer by Sunlight Gardens.
• Matelea reticulata (Green milkweed vine) blooms April through June.
• Matelea sagittifolia (Arrowleaf milkvine) blooms in March and April.

Of course, you won't be able to find many of these for sale commercially, but you will find some of them available at the Wildflower Plant Sale—the next one being Octobe 9-11, 2015.  You should also check our National Suppliers Directory to find seed companies and nurseries near you that deal in native plants.  The Native Plant Society of Texas—NPSOT (Austin Chapter and Williamson County Chapter are the closest to you) often have sources for native plants or seeds.

Queens do migrate when they get the environmental signals that it's time to go and are not too likely to be around during the colder parts of winter; but, here is a link to the Texas Butterfly Ranch with help on what to feed late season Queens that get caught by a cold front for several days with little in the way of nectar plants for food/fuel.