Subject: Caterpillar id
Location: Big Lake, Minnesota
May 30, 2016 3:29 am
Good morning. My sister has caterpillars in her semi woodland garden in Big Lake Minnesota that are literally dropping from the trees (pine and ornamentals) on the margin of the woodland. They seem to be most active now – mid May. It is her first summer there so cannot say whether this is unusual.
Ed. Note: We had an offline exchange with Lorna since the image attached to the original email was a Black Arches Caterpillar from our site. We finally received the correct image.
Oops. I don’t know how that happened – I am sorry. Here it is:
The general term Cankerworm is used to describe several species of Inchworms or Spanworms that feed in trees and drop to the ground. According to Virginia Green Lawn Care: “The term ‘canker worm’ is used, not to describe a single caterpillar, but a group of inchworms that cause damage to many different ornamental and fruit trees. … These leaf eating insects are not only a nuisance; they can cause great damage or even destroy a grown tree over a period of time. You may have run into one dangling from a silk thread as you walked under a tree. It is a battle between canker worms and the trees you love and have planted and nurtured. When heavy populations are present, they can completely defoliate a tree in just a few weeks. This is when you need to step in.” The individual in the new image you attached looks like the Linden Looper, Erannis tiliaria, a species that according to BugGuide feeds on: “Deciduous trees, including apple, ash, beech, birch, elm, maple, oak, poplar, Prunus and Ribes.”