Monday, August 30, 2010

Get ready for monarchs!

Female Monarch

In the desert summer lasts forever! What are signs of Fall? In Northern climates, leaves begin to change colors. Here in the desert, the large and elegant regal orange monarch butterflies appear on their Fall migration!

Male Monarch
Monarch butterflies are the only insect with a long range and impressive annual migration. Tropical in nature, they can only survive in temperatures above freezing. During the summer months monarchs are in their breeding grounds. East of the Rockies monarchs breed in the Northern tier of the United States and Southern Canada. West of the Rockies the breeding grounds are not as well known. We do know that we have several breeding hot spots in Arizona in Springerville, Arivaca Cienega, Canelo, St. David Cienega and likely more. Where these monarchs moved from is not currently known.

2009 Southwest Monarch Study "Recent Sightings"
So, it's time to get ready for the monarchs in Phoenix! Last year they were first spotted at South Mountain on September 10th and the Desert Botanical Garden the next day. What triggered their arrival? Likely two things. First, the peak migration time for the Phoenix area is predicted as the time interval from September 29 through October 11th. Perhaps the best way to look at the migration is a marathon race in the Olympics. When the start signal flares, a few runners surge ahead, then there is the main body of runners, and finally the stragglers. Monarchs seem to have similar movements. The early leaders of the pack can arrive up to thirty days before the time of the peak migration. In the Phoenix area we have a limiting factor - our temperatures. 104 in laboratory studies is a critical temperature when monarch mortality increases. By 108 there is widespread mortality. Last year temperatures cooled around the fifth of September. The monsoons receded and nightime temperatures eased to the low 70's, offering a relief to balance the higher daytime heating. The surge in monarch sightings last year occurred during the week ending September 15th when migrating monarchs began to appear in addition to presence of breeding monarchs around the state. You can also note the second increase of monarchs appeared during the anticipated time of peak migration.

Lantana is a butterfly favorite!
How to get your yard ready so monarch will visit? If you haven't already, lightly fertilize monarch favorite exotic (versus native) nectar plants like lantana, zinnia or Tropical Milkweed. A light dose of Bone Meal or a half strength solution of a liquid fertilizer watered in well will help revive heat ravaged plants. Keep sensitive to high daytime temperatures to avoid burning your plant. Gently trim any straggly growth to encourage new leaves. Again, less is more when the temperatures are high, but light trimming is beneficial to creating new blooms.Take care when you gently trim Tropical Milkweed - queen butterflies are busy laying eggs and you don't want to lose the offspring of these family members of the monarchs.

Female monarch butterfly on marigolds
Taking a few moments now to water deeply, lightly pruning and gently fertilizing can help the flowers monarch butterflies love surge with new growth and lush flowers to welcome these jewels of the butterfly world when they swoop in to our desert gardens.


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