Monday, November 9, 2015

House of Straw

Grass-carrying wasp nest - Chris Barnhart.
Little pigs aren't the only animals that build their house out of straw.  Chris Barnhart spotted this grass sticking out of a carpenter bee hole in the fascia of our cabin and taught me about grass-carrying wasps.

Isodontia - Robert Lord Zimlich
This is a nest of the Isodontia wasp species.  They use grass, or sometimes inner fibrous bark or Spanish moss to line cavities in trees, other species' nests and even house window edges, sealing a chamber which holds their brood of several larvae.  Their eggs are provisioned with paralyzed crickets or occasionally grasshoppers, usually picking the small ones for ease of transport.  Their prey will remain alive but immobile (think zombies) as they are consumed, fresh food without the freezing.

Generally benign, they are capable of stinging if handled although few of us would be tempted to grab a wasp, with or without straw.  You can watch them in action on this video by Dick Walton.

Isodontia mexicana - Styrulus EOL CC
One of the grass-carrying wasps has reversed the direction of the Columbian Exchange that brought us so many benefits and invasive species from Europe.  Isodontia mexicana has accidentally been introduced to France and is spreading across Europe, lacking natural predators.  Apparently French insects aren't aware of the three little pigs and the techniques of blowing the grass out.

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