Friday, December 30, 2011

Phoenix Area Monarch Butterflies

Late Wednesday afternoon Bob and I went out to cover our plants for one more night of possible freezing temperatures. As I walked by the Sweet Almond tree, Aloysia virgata, I saw a flutter of orange on the ground - a freshly eclosed male monarch attempting its first flight. The temperatures were already dropping and its wings were not fully hardened. As I looked up at the tree, I spotted this dark monarch chrysalis. The previous night the temperatures dipped to 31 degrees and I wasn't sure if the chrysalis was viable so I brought it inside. (The monarch eclosed two hours later successfully.) As I lifted the frost cover in another part of the yard to cover more plants another freshly eclosed monarch flapped its wings in greeting! All this activity is so rare for the end of December in the Phoenix area.

Last week I shared that a female monarch #60061 tagged on 11/19 (eclosed 11/18) in my backyard was seen in Kino Bay, Sonora on 12/14 by Gail Rochlin. Scientists have learned that temperatures and sun angle are important triggers of the monarch migration among other factors.  The celestial influence weakens in late November and most directional flight ceases by the beginning of December. Here you can see monarch #60421 tagged in my yard on 11/25 (eclosed 11/24) sunning and later nectaring on tithonia still in my yard yesterday. That is a difference of only six days of when they eclosed. The sun angle for #60061 was 37.31. The sun angle for #60421 was 35.99. One migrated. One stayed. There likely isn't an exact migration cut-off date or maybe one of these bugs just didn't read the "how to migrate rules" to follow. Just interesting stuff.

With warming temperatures climbing to the mid-70's for the next week we will hopefully see more butterfly activity. Check out the activity we saw at Rio Salado Habitat Restoration Area in Phoenix yesterday: 

If you decide to visit Rio Salado, please stay on the trails and enjoy this natural wonder. Touching, capturing or removal of monarch butterflies, or future eggs, larvae or pupae is prohibited by law and hidden cameras are recording the area for the preservation of the habitat.

We've had a cool December in the Phoenix area and many people are still reporting monarch larvae, pupae and adults around town in Paradise Valley, Phoenix, Scottsdale, Chandler, Mesa and Ahwatukee. Monarchs are tropical by nature and are affected by freezing temperatures. Unless we have a hard freeze there is a chance some of these monarchs may survive our winter this year. (The National Weather Service Winter Outlook  gives a glimpse of the next few months in Arizona.) It's a good idea to keep some of the favorite nectar plants of monarchs around to encourage them to visit your yard on warm, sunny days. Besides lantana and verbena which can look a bit cold stressed this time of year, look for some of these nectar favorites still available in local nurseries:

 Fern-leaf Lavender, Lavandula minutolli
(Monarchs are picky about lavenders - this is the only lavender we see them use for nectar.)

Marigolds, Tagetes spp.

Baja Fairy Duster, Calliandra californica

Calendulas, Calendula spp.



  1. How wonderful that you are still seeing monarchs. Beautiful pictures! Here we are already excited when we see the odd hummingbird still at the feeder.

    I just saw some unidentified small butterfly go by as I sit here at the computer. Very little blooming to help it out however. Our nights have been down to 13 but were above freezing last night.

  2. Thanks so much for all the detail, it's very exciting to read about the monarchs you found in your garden. Wonderful photographs and great blog post!