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Wednesday, October 20, 2010

Milkweed Snails

During yesterday's rain I noticed two small snails, Helix aspersa of course, midway up a milkweed plant.  I've seen snails on the milkweed before, and it always seems like a surprise, like snails would not eat milkweed.  I probably am biased this way because the latex of milkweed burns my skin and so I assume it would be very unpleasant to a snail's soft mucous-y parts (think . . . salt).  But here they are.

Other people seem to have the same uncertainty as regards the snail/milkweed relationship.  When I google "snails on milkweed" I find several to many articles and blog posts expressing surprise, like me.  But there they are, the snails on milkweed that is.

On a slightly different note, have you noticed how quickly an established milkweed plant rebounds after being defoliated?  This article suggests that milkweed is evolving its survival tactic away from production of toxic defenses and toward quicker regrowth.  I have often marveled at the diverse and very populous nature of Bugs That Feed on Milkweed, given the fame of the milkweed toxins and latex defense.

So, maybe the milkweed latex and toxins (cardenolides) aren't what they used to be and snails have taken advantage of a new food source?  Still, the latex burns my skin.  Maybe I'm not as tough as snails.

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