Recently Jared Del Rosso posted about wondering what a northern shrike and Say's phoebe might be foraging for in a field at Denver's Willow Spring Open Space. I responded by guessing they might be after the caterpillar stage of the army cutworm moth (Euxoa auxiliaris, aka "the miller moth"). Other possibilities might be adult midges, one of the hardy ichneumon wasps and a hardy robber fly that we have in this area. Another possibility I neglected to mention but should have are some of the grasshopper species that overwinter as adults and nymphs.
I have had a couple inquiries about the subject and offer the following. Below are pics from a few years ago of a loggerhead shrike with an unidentified cutworm larva and a mass of army cutworm larvae, both pics taken in April north of Fort Collins and near Fort Morgan, respectively, when the larvae would be bigger and more conspicuous at the base of plants or crawling across bare ground than they would be in early March.
For more information, "Miller Moths" was the title of the very first "The Hungry Bird" column in the CFO journal "Colorado Birds" back in April 2010 (volume 44, #2). This is archived on the CFO website.
Dave Leatherman
Fort Collins
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