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Of Monarchs and Milkweed

common-milkweedCommon Milkweed at Behnke’s

We have a couple of patches of common milkweed (Asclepias syriacus) growing on the grounds of the garden center.  These were not intentionally planted, they started as seedlings from some errant seed dropping in by parachute at some point in the past.  You’ve seen these seed parachutes yourself, but probably did not know what they are.  When I was a kid, we’d see these little round fluffballs drifting on the wind and we called them “wishes.”  If you caught one, your wishes would come true.  The seed is suspended from the base of the parachute and at some point is dislodged, leaving the ‘chute to float until it gets tangled up in something.

asclepias-tuberosa-seedpodsButterfly Milkweed Seedpods

We don’t sell common milkweed.   Even though Asclepias is the sole food source for monarch butterflies, this particular one doesn’t make a very good garden plant. It spreads quickly underground like bamboo, and the foliage isn’t particularly attractive (although the waxy pale pink flowers are quite nice).  We have tried to grow it in pots a few times, but lost most of it.  For a rampant weed, it’s fussy about “pot culture.”  We carry two other perennial milkweeds, the Butterfly Milkweed (Asclepias tuberosa), with nice orange flowers in early summer, and the Swamp Milkweed (Asclepias incarnata), with white or deep pink blooms in early summer.  Monarch caterpillars also will feed on those.  These are best planted in the late spring/early summer.  Both are doing quite well in the Pollinator Garden we planted in the summer of 2015.

monarch-caterpillarMonarch Caterpillar

We were excited at this writing (September 7) when we spotted a half a dozen monarch caterpillars on the common milkweed.  I’ve been looking for these (not continually) for close to 60 years, and it’s the first time I’ve actually seen them.  We hope they eat their fill, make a chrysalis, hatch, and fly west.  It’s very nice to know that we’ve made a contribution to the great monarch migration.

Update: Even more excited today (September 14), because we saw a mother-to-be monarch laying eggs on the plants.  She hovers around, lightly touching down and tapping her abdomen to the leaf (mostly on the underside), and deposits an egg.  This is a movement reminiscent of something my Pilates trainer keeps trying to get me to do:  “Okay, legs out straight and pointing to the mirror. Lightly tap your feet to the ground and right back up!”  Thud.  Also no egg.

monarch-eggsMonarch Eggs

She then flits off to a new leaf, as only a butterfly can flit.  The small greenish eggs are laid individually, not in a mass, and are about the size of an aphid.  Since milkweeds almost always have aphids, the comparison of size is easy.  Soon they will hatch and we’ll have another crop of monarchs, hopeful that it’s soon enough to make it for the fall migration.

by Larry Hurley, Behnke horticulturist

Larry Hurley, perennials specialist for Behnke Nurseries (now retired), started with Behnke’s in1984. Larry enjoys travel, food and photography. He and his wife Carolyn have visited Australia, New Zealand, Thailand, Brazil, South Korea and much of Europe. Their home is on a shady lot where a lot of perennials have met their Maker over the years.

This Post Has 3 Comments

  1. Larry, thank you so much for your milkweed and monarch tribute! As a child my family and cousins made an annual summer trip to Kennebunk, Maine where my maternal grandparents had a summer home with, what seemed to us then, a huge, sloping back yard (3 acres or so) with the very last section against the woods left in its natural state and bursting – literally! – with milkweed and its irresistible, fluffy pods. It was one of our greatest summer delights (and learning experiences in our grandfather’s wonder-filled gardens) to carry jars down to the meadow to look for caterpillars and chrysalides, carefully pick choice specimens for our makeshift terrariums and watch the miraculous processes unfold as the summer progressed. I have retained a special fondness for milkweed ever since (as well as Queen-Anne’s Lace which also graced that meadow), and delight in the discovery and photographic possibilities of similar meadows nearby, and the memories they stir. Thanks for stirring them up again!

  2. My swamp milkweed was full of caterpillars a few days ago. Now there are no caterpillars, most of the leaves have been consumed and what is left contains small orange “eggs?” Is this normal?. This is my first swamp milkweed. I purchased it to help with the monarch population. I don’t know what to expect.

  3. Mary Jo,

    This is late in the season for Monarch caterpillars to be around; they are probably wandered off to form a chrysalis and emerge as adults so they can begin migrating. Most caterpillars will leave their host plant when pupating so the predators that cue in on damaged leaves don’t find them in their most vulnerable stage. The “eggs” are likely actually Oleander Aphids which are very commonly found feeding on milkweed sap. Despite the high numbers of them I have seen this year, they are not a major problem and any pesticide applied to remove them will harm the Monarchs and other pollinators as well. A hard jet of water will blast many of them off, but it would have to be done repeatedly.

    – Miri, woody plants dept.

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