Euxoa auxiliaris
In 3 days ~20% in a week ~40%
The army cutworm is the immature form of Euxoa auxiliaris. Together with other moths that are locally abundant and that have scales that dislodge from the wings, the adult moth is called a miller moth. These native North American larvae consume emerging small grains, alfalfa, and canola in the Great Plains and southern Canada.
On dry, low elevation rangelands of the U.S. Intermountain West, army cutworms consume exotic cheatgrass (Bromus tectorum) and mustards to produce cheatgrass "die-offs." Within these bare areas, the larvae also defoliate native shrubs including four-wing saltbush (Atriplex canescens) and sagebrush (Artemisia spp.).
Army cutworms have only one generation per year. Adult moths lay eggs in the fall at low elevations in the Great Plains and U.S. Intermountain West. Larvae hatch in late fall and feed, mostly at night, through the winter and into spring.
The larvae pupate in the soil in late spring and emerge as adult miller moths. The moths soon migrate to high elevations for the summer. Miller moths are a seasonal nuisance during their seasonal migrations through states including Montana, Idaho, Nevada, Texas, Oklahoma, Colorado, Wyoming, New Mexico, and Kansas.
Moths that emerge in the Great Plains migrate to high elevations in the northern Rocky Mountains, where they are an important food for grizzly bears. Moths that emerge in the Intermountain West migrate to nearby mountain ranges, such as the Jemez Mountains of New Mexico and the mountains of Great Basin National Park in eastern Nevada, where a 2014 Lepidoptera BioBlitz found "blizzard of adult army worm moths (Euxoa auxilliaris), which were present in millions."
Miller moths return to low elevations as the weather cools in fall, but in smaller numbers. Although many consider the moths to be a nuisance, the insects pollinate plants and are food for bats. Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|
More parks will be added in future updates.
| # | City | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Denver | 🇺🇸 United States | |
| 2 | Salt Lake City | 🇺🇸 United States | |
| 3 | Mesa | 🇺🇸 United States | |
| 4 | Dallas | 🇺🇸 United States | |
| 5 | Austin | 🇺🇸 United States | |
| 6 | Los Angeles | 🇺🇸 United States |
With luck
About 10% of wildlife watchers report an Army Cutworm Moth sighting in Denver on a given day, based on 72 verified sightings from GBIF citizen-science data. It is the 87th most-seen of the 461 insects we can rate there. Over three days the chance rises to about 20%, and over a week to about 40%, if each day is a fresh chance.
May
In that month about 20% of wildlife watchers report an Army Cutworm Moth in Denver on a given day, against under 5% in July–August and November–April, the lowest months. That is one of Denver's wettest months, with about 60 mm of rain against 15 mm in January.
Yes
Of the 6 cities where we can rate Army Cutworm Moth sightings, Denver has the highest daily chance: about 10%. Next come Salt Lake City (United States, under 5%) and Mesa (United States, under 5%).
Same family: Noctuidae
The closest relatives of the Army Cutworm Moth that you can see in Denver (family Noctuidae, Cutworm Moths and Allies) are Corn Earworm Moth (about 10%), American Dagger (about 10%) and Large Yellow Underwing (about 10%), with each one's daily chance of a sighting.
GBIF citizen-science records
It is estimated from how often the Army Cutworm Moth is recorded against all the insects logged in Denver (72 verified sightings), calibrated against known sighting rates. Figures are rounded to the nearest 10% because citizen-science data supports honest approximations, not decimals, and months with records from fewer than five people show "—". How it works.
