Tuesday, June 2, 2015

To Err is Human - An Adventure in Mis-Identification

On May 21st, I wrote a short post about what I thought were caterpillars attacking the columbine plants in our garden.  We brought several of these larvae into the house and put them in a small container for closer observation.  After a few days, many of these larvae had spun cocoons.

On Monday (01 JUN) we returned home from work to find that something had emerged.

My first thought upon seeing what had emerged from the cocoon was that a wasp had parasitized the caterpillar and consumed the developing butterfly within the cocoon.

Columbine Sawfly adult and cocoon - photo by Shara LeValley

However, upon further research I realized that I had misidentified the larvae on the columbine plants.  They were not the Columbine Duskywing butterflies (Erynnis lucilius) that I originally thought.  Instead they were the larvae of the Columbine Sawfly (Pristiphora rufipes).  The wasp-like insect is an adult sawfly.  They belong to the order Hymenoptera along with ants, bees, and wasps.  The larvae of sawflies are often confused with moth or butterfly caterpillars, in part because they resemble caterpillars and also because they usually feed on leaves like a caterpillar.  Adult sawflies look very much like wasps, but can be distinguished by their thick "waist".

I have seen sawflies before, but still misidentified these larvae as caterpillars.  I learned something new today.

Columbine Sawfly - photo by Shara LeValley

Columbine Sawfly on Garden Columbine - photo by Shara LeValley

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