Callophrys affinis
In 3 days ~20% in a week ~40%
Callophrys affinis, the western green hairstreak or immaculate green hairstreak, is a butterfly of the family Lycaenidae. It is found in western Canada and the western United States. The wingspan is 20 to 28 mm. Adults are on the wing from early March to mid-June in one generation.
The larvae feed on Eriogonum umbellatum. Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Grand Canyon National Park | 🇺🇸 United States | |
| 2 | Rocky Mountain National Park | 🇺🇸 United States |
With luck
About 10% of wildlife watchers report a Western Green Hairstreak sighting in Rocky Mountain National Park on a given day, based on 20 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 97th most-seen of the 191 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.
April to June
In those months about 10% of wildlife watchers report a Western Green Hairstreak in Rocky Mountain National Park on a given day, against under 5% in July to March, the lowest months.
Between 10 am and 1 pm
Across all the parks we cover, that three-hour window holds the most Western Green Hairstreak sightings with a recorded time, and nearly all of them come between 6 am and 6 pm: it is a daytime animal.
Among the best
Of the 2 parks where we can rate Western Green Hairstreak sightings, Rocky Mountain National Park ranks 2nd at about 10%, level with the leaders once rounded. The best odds are in Grand Canyon National Park (United States, about 10%).
GBIF citizen-science records
It is estimated from how often the Western Green Hairstreak is recorded against all the insects logged in Rocky Mountain National Park (20 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.
