Orgyia pseudotsugata
In 3 days ~20% in a week ~30%
Orgyia pseudotsugata, the Douglas-fir tussock moth, is a moth of the subfamily Lymantriinae first described by James Halliday McDunnough in 1921. It is found in western North America. Its population periodically irrupts in cyclical outbreaks. The caterpillars feed on the needles of Douglas fir, true fir, and spruce in summer, and moths are on the wing from July or August to November.
Adult males are grayish brown moths with mottled light and dark markings. The males' wingspread is 25–34 mm (0.98–1.34 in). When the wings are spread open, the brown hindwings can be seen. Individuals in the northern part of its range are darker and southern populations are lighter. Antennae are plumose (feathery). Females are flightless with only rudimentary wings. Larvae (caterpillars) are 20–26 mm (0.79–1.02 in) and colorful with red spots, white spines, conspicuous red-tipped white tufts or "tussocks", and dense bunches of long, black hairs projecting to the front and behind.
The Douglas-fir tussock moth is native to forests of western North America and outbreaks have been identified in British Columbia, Idaho, Washington, Oregon, Nevada, California, Arizona... Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Sequoia and Kings Canyon National Parks | 🇺🇸 United States | |
| 2 | Yosemite National Park | 🇺🇸 United States |
| # | City | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Denver | 🇺🇸 United States |
With luck
About 10% of wildlife watchers report a Douglas-Fir Tussock Moth sighting in Yosemite National Park on a given day, based on 11 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 116th most-seen of the 227 insects we can rate there. Over three days the chance rises to about 20%, and over a week to about 30%, if each day is a fresh chance.
August
In that month about 20% of wildlife watchers report a Douglas-Fir Tussock Moth in Yosemite National Park on a given day, against under 5% in September to June, the lowest months. That is one of Yosemite National Park's driest months, with about 30 mm of rain against 220 mm in January.
Between 8 and 11 am
Across all the parks we cover, that three-hour window holds the most Douglas-Fir Tussock Moth sightings with a recorded time, and about 9 in 10 of them come between 6 am and 6 pm: it is a daytime animal.
2nd of 2
Of the 2 parks where we can rate Douglas-Fir Tussock Moth sightings, Yosemite National Park ranks 2nd at about 10%. The best odds are in Sequoia and Kings Canyon National Parks (United States, about 20%).
Same family: Erebidae
The closest relatives of the Douglas-Fir Tussock Moth that you can see in Yosemite National Park (family Erebidae, Underwing, Tiger, Tussock, and Allied Moths) are Silver-Spotted Tiger Moth (about 20%), Isabella Tiger Moth (about 10%) and Wild Forget-Me-Not Moth (about 10%), with each one's daily chance of a sighting.
GBIF citizen-science records
It is estimated from how often the Douglas-Fir Tussock Moth is recorded against all the insects logged in Yosemite National Park (11 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.
