Nematocampa resistaria
In 3 days ~10% in a week ~30%
Nematocampa resistaria, the filament bearer, bordered thorn or horned spanworm moth, is a moth of the family Geometridae. The species was first described by Gottlieb August Wilhelm Herrich-Schäffer in 1856. It is found in North America from British Columbia to Nova Scotia, south to Florida and California.
This species was split from the Eurasian Nematocampa limbata. The wingspan is 19–25 mm. Adults are on wing from May (or April in the deep south) to August. There is one generation in the north, two generations in the middle states and multiple generations in the southern part of the range.
Larvae feed on various deciduous and coniferous trees and shrubs, including Pseudotsuga, Tsuga, Abies, Picea, Salix, Betula papyrifera, Corylus, Fragaria and carrot (Daucus). Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Glacier National Park | 🇺🇸 United States | |
| 2 | Great Smoky Mountains National Park | 🇺🇸 United States |
| # | City | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Austin | 🇺🇸 United States | |
| 2 | Toronto | 🇨🇦 Canada | |
| 3 | Minneapolis [Saint Paul] | 🇺🇸 United States | |
| 4 | Boston | 🇺🇸 United States | |
| 5 | Edmonton | 🇨🇦 Canada | |
| 6 | Chicago | 🇺🇸 United States | |
| 7 | Houston | 🇺🇸 United States | |
| 8 | Montreal | 🇨🇦 Canada | |
| 9 | New York City | 🇺🇸 United States | |
| 10 | San Antonio | 🇺🇸 United States |
Rare
Under 5% of wildlife watchers report a Horned Spanworm Moth sighting in Great Smoky Mountains National Park on a given day, based on 16 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 513th most-seen of the 822 insects we can rate there. Over three days the chance rises to about 10%, and over a week to about 30%, if each day is a fresh chance.
June
In that month about 10% of wildlife watchers report a Horned Spanworm Moth in Great Smoky Mountains National Park on a given day, against under 5% in July to May, the lowest months.
Between 10 pm and 1 am
Across all the parks we cover, that three-hour window holds the most Horned Spanworm Moth sightings with a recorded time, and about 6 in 10 of them come between 6 pm and 6 am: it is seen both by day and at night.
2nd of 2
Of the 2 parks where we can rate Horned Spanworm Moth sightings, Great Smoky Mountains National Park ranks 2nd at under 5%. The best odds are in Glacier National Park (United States, about 10%).
Same family: Geometridae
The closest relatives of the Horned Spanworm Moth that you can see in Great Smoky Mountains National Park (family Geometridae, Geometer Moths) are Tulip-Tree Beauty (about 30%), White-Striped Black (about 20%) and Pale Beauty (about 20%), with each one's daily chance of a sighting.
GBIF citizen-science records
It is estimated from how often the Horned Spanworm Moth is recorded against all the insects logged in Great Smoky Mountains National Park (16 verified sightings from 2019 to 2026), 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.
