Monday, June 8, 2015

Milkweed Traps

A skipper butterfly sips nectar while its moth cousin has gotten stuck and cannot get loose.

Another moth that was too weak to remove the pollen sacs and died.

While a hairstreak butterfly feeds, an unlucky moth dangles dead when it could not free itself.

     Something many people are not aware of what goes on unseen on the milkweeds in bloom right about now. Most people are aware of how attractive these flowers are to insects. Not only are they covered in many pollinators during the day, but are very active at night as well, especially with moths and beetles. Some milkweeds, like Common Milkweed (Asclepias syriaca), are specially fragrant and attract numerous insects both day and night with their rich nectar supply. But many of these pollinators who are attracted are not designed to remove the pollinia (pollen sacs) that milkweed have and are not the proper pollinators.
     Pollinia (singular pollinium) are pollen grains that are grouped and stuck together, designed to be moved as a unit, like a single structure. They almost look like small saddlebags in milkweeds. It takes large specialized pollinators to move them properly. Those that are too weak are sometimes trapped and may lose legs trying to escape, or even die. Here are a few photos from a single milkweed patch on one day showing a collection of small moths who were unable to get away and died. Most have stuck legs, but a few had their proboscis stuck as well. Others are scavenged by the many insects that patrol the flowers and so they are not around for long. That means that this is but a small number of the insects who got themselves trapped. It can be dangerous being a pollinator.
     Here's a European Honeybee who likewise got itself trapped. Note the pollinia stuck to its legs.

A European Honeybee trapped on a Swamp Milkweed. Note the pollinia stuck to its legs. 

     Here is a short video from the Capital Naturalist YouTube Channel that shows the struggle a honeybee goes through after getting trapped by the pollinia:
      It's amazing the drama that goes on on a miniature scale in nature, even on something as beautiful and harmless looking as a flower...

A Banded Tussock Moth trapped on Common Milkweed.

A Green Bottle Fly hangs dead after trying to steal nectar.


  1. Youtube link:

  2. Thank you folks, looks like it'll have to be cut and paste for the video. Thank you.