Boisea rubrolineata
In 3 days ~20% in a week ~30%
Boisea rubrolineata or the western boxelder bug is identical to the eastern boxelder bug aside from having prominent red veins on its corium. It is found in western North America. Adults are 9–13 mm in length. The thorax and wings are black with red lines, and the abdomen is red. Nymphs are bright red and gray. Both nymphs and adults feed on boxelder. In fall and winter, adults might be noted migrating indoors to hibernate. Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Yosemite National Park | 🇺🇸 United States | |
| 2 | Sequoia and Kings Canyon National Parks | 🇺🇸 United States |
| # | City | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Portland | 🇺🇸 United States | |
| 2 | Sacramento | 🇺🇸 United States | |
| 3 | San Francisco | 🇺🇸 United States | |
| 4 | Seattle | 🇺🇸 United States | |
| 5 | Los Angeles | 🇺🇸 United States | |
| 6 | San Diego | 🇺🇸 United States |
With luck
About 10% of wildlife watchers report a Western Boxelder Bug sighting in San Francisco on a given day, based on 269 verified sightings from GBIF citizen-science data. It is the 75th most-seen of the 737 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.
February to May
In those months about 10% of wildlife watchers report a Western Boxelder Bug in San Francisco on a given day, against under 5% in June to January, the lowest months.
Between 2 and 5 pm
Across all the parks we cover, that three-hour window holds the most Western Boxelder Bug sightings with a recorded time, and about 9 in 10 of them come between 6 am and 6 pm: it is a daytime animal.
3rd of 6
Of the 6 cities where we can rate Western Boxelder Bug sightings, San Francisco ranks 3rd at about 10%. The best odds are in Portland (United States, about 30%) and Sacramento (United States, about 20%).
GBIF citizen-science records
It is estimated from how often the Western Boxelder Bug is recorded against all the insects logged in San Francisco (269 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.
