Tuesday, November 22, 2016

Restoring Bottomland Prairie, 2016: Monarchs & Milkweeds, Pests & Pollinators

A Monarch larva (Danaus plexippus)
on Common Milkweed
(Asclepias syriaca)
A Monarch caterpillar on Common
Milkweed.  Creek Field, 2016
Monarch butterflies have yet to appear in large numbers in our bottomground early in the growing season, when the Common Milkweed is blooming.   In fact, these two photos show the only Monarch caterpillar I have ever found on Common Milkweed in our restoration.

With Swamp Milkweed, it's a different story! 
Monarch caterpillars munch
on Swamp Milkweed leaves.

Every year in August and September, when Asclepias incarnata blooms in our wetland areas, it is covered with Monarch caterpillars--and many other creatures, as well.

Here a Monarch caterpillar on Swamp Milkweed forms a backward "J," indicating that it's getting ready to pupate.    

The tiny round yellow-orange creatures are aphids!

They can strip the milkweed bare.

But nature has its checks and balances.

Here is a Syrphid fly larva on the Swamp Milkweed stem, moving in on that aphid on the right.    The larva's purpose in life?  To eat aphids!

Toxomerus politus, getting minerals from the
surface of my skin, August 2016.
Though a fly, this species is a bee-mimic.
Resembling creatures that can sting is a
good protection!
This year there was a big burst of the Syrphid fly shown here (Toxomerus politus).  This species may or may not be the parent of the larva pictured above (bugguide.net has a project underway to determine the species of Syrphid larvae--hard to do without DNA analysis).    But either way, the m.o. is the same:  The adult fly eats pollen, getting enough protein to lay eggs.  Then she drinks sugar-filled nectar to fuel energy-expensive flights from plant to plant.   As she flies, inadvertently pollinating as she goes, she looks for aphid colonies.  When she finds one, she lays her eggs on a stem next to the infestation.   By the time the eggs hatch, the aphids will have moved to that very location.   Yum!

Pollinators other than Monarchs love the late-blooming Swamp Milkweed as well.  

 Here is a Dun Skipper (Euphyes vestris) nectaring on Swamp Milkweed.   She is one of the subtly patterned but absolutely adorable Grass Skippers.  Those eyes!  That cape!    This one lays eggs on sedges, the larval food plant.  

 Though the Monarchs munched heartily, as shown in the video above, and aphids & milkweed bugs took their toll, the Swamp Milkweed still had enough energy to produce abundant seeds.  

The seeds of Asclepias incarnata dispersing, Sept. 2016
Here the seeds of  Swamp Milkweed disperse on the September wind.

I had been worried because the constant spring rains had turned the wetland into a deep pool.   Swamp Milkweed is a perennial that likes wet feet, but could it survive being underwater for a month?    I was relieved when right on schedule it leafed out and bloomed.

The seeds promise even more Swamp Milkweed next year!