Subject:  Green Caterpillar
Geographic location of the bug:  Angela, Montana
Date: 08/07/2019
Time: 02:43 PM EDT
Your letter to the bugman:  My daughter found this by some of our grain bins and she loves bugs. Just curious what kind it was. Thanks!
How you want your letter signed:  Hadlie Mae

Glover’s Silkmoth Caterpillar: Hyalophora species

Dear Hadlie,
This is a Giant Silkmoth Caterpillar in the genus Hyalophora, but we are not certain of the species.  BugGuide recognizes three species in North America, and BugGuide reports two of those species, the Ceanothus Silkmoth and the Columbia Silkmoth from Montana, and the third species, the Cecropia Moth, is reported from the nearby Dakotas as well as Wyoming, and since Angela, Montana is in the eastern half of the state, we would not rule out the Cecropia Moth.  We will try to contact Bill Oehlke to see if he can distinguish the actual species.  Here is a BugGuide image of the Glover’s Silkmoth Caterpillar, the western subspecies of the Columbia Silkmoth.  We suspect your caterpillar is preparing to spin a cocoon.

Giant Silkmoth Caterpillar: Hyalophora species

Thank you! He stared to change the night we emailed you.

Giant Silkmoth Cocoon

Hi again Hadlie,
Thanks so much for sending in images of the cocoon spun by your Giant Silkmoth Caterpillar.  We are hoping to hear back from Bill Oehlke regarding a species identification.

I am pretty sure it is Columbia gloveri due to three sets of orangey dorsal scoli instead of two sets in cecropia. Both species are likely present in Rosebud County.
Bill Oehlke

Location: Angela, Montana

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