Saturday, February 26, 2011

The Monarch Spring Migration

Desert Botanical Garden 3/6/09
Dr. Chip Taylor, Director of Monarch Watch, posted an important reminder this week: Monarch butterflies in Mexico are on the move! Monarchs begin mating around Valentine's Day and a few begin to leave their winter haven slowly in the following weeks. First monarch sightings in Texas are usually reported by the end of the first week of March. What about Phoenix? Last year we spotted a weathered female monarch laying eggs at the Desert Botanical Garden on March 15th. In 2009 we found four monarch larvae in the Herb Garden on March 6 - overwintering monarchs mated in mid-February.

Tatsuyo, South Mountain, 2-24-11
Monarch presence and absence are not well understood in the Phoenix area. Observations vary from year to year. Our warm Fall and early Winter encouraged more monarchs to lay eggs through December. Three freezes, two of them hard freezes, decimated monarch populations at the Desert Botanical Garden and Tempe Marsh. But a few monarchs survived at Rio Salado and on South Mountain in Tatsuyo's yard. So far in February ten monarchs eclosed at her house - these two females were released on their way on Thursday. There are possibly others in hidden niches around town, too.

The occasional rare hard freezes and the last (hopefully) cold storm of the season tonight and tomorrow are testing monarch nectar and host plants around town. Sunday night may bring freezing temperatures to parts of the greater Phoenix area, so get ready to cover plants again. If you already have frost-sensitive plants growing, you can give them additional protection from freezing temperatures by placing jugs of hot water around them for the night. Our sunflowers survived the last hard-freeze with this added coverage.

Monarch visiting calendula
After the weekend's cold temps pass, you can also find calendulas, fernleaf lavender, lantana, coreopsis and ageratum in local nurseries as quick nectar sources for migrating monarchs. Of course, keep milkweed available as a host plant.

Desert Ageratum
Spring Plant Sales are right around the corner! Milkweed tops the list as a monarch and queen host plant but also one of the most popular nectar sources for ALL butterflies. For the Phoenix area be sure to see Monarch Milkweed Wish List. Here are a few good general resources to consider while creating your plant shopping list:
Desert Gardening Guides - Desert Botanical Garden
"Landscape Plants for the Arizona Desert" - AZ Municipal Water Users Association
Plants for the Desert Southwest - Mountain State Nursery

Upcoming Plant Sales 
Boyce Thompson Arboretum
Superior, AZ
March 11 - Members only
March 12 to 27 Public

Desert Survivors
Tucson, AZ
March 12 - 18 Members only
March 19 - 20 Public   

Desert Botanical Garden
Phoenix, AZ
March 18 - Members only
March 19 - 20 Public

Tohono Chul
Tucson, AZ
March 16 - Members only
March 19 - 20  Public

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