Prionus californicus
In 3 days ~40% in a week ~70%
Prionus californicus, commonly known as the California root borer, is a species of insect in the longhorn beetle family (Cerambycidae). It is native to the American west where it is often a pest of orchard and vine crops.
The California root borer occurs widely in western North America from Alaska to Mexico. It spends most of its life underground feeding on the roots of most deciduous trees and shrubs, as well as some conifers, brambles, and agricultural crops such as hops and grape vines.
The 2.5 to 5.7 cm adults, which are reddish-brown with smooth shiny wing-cases, emerge from the soil from June to early August. The males are smaller than the females and have more strongly serrated antennae. The adults do not feed. They fly at night, seeking mates. Males appear to be more active, while females produce a pheromone to attract males. The female-produced sex pheromone compound has been identified as an isomer of 3,5-dimethyldodecanoic acid. A synthetic mixture of all four possible isomers of 3,5-dimethyldodecanoic acid is highly attractive to male P. californicus in field trials.
The life span of the adult P. californicus is 10... Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Sequoia and Kings Canyon National Parks | 🇺🇸 United States | |
| 2 | Yosemite National Park | 🇺🇸 United States | |
| 3 | Channel Islands National Park | 🇺🇸 United States | |
| 4 | Grand Canyon National Park | 🇺🇸 United States |
| # | City | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Salt Lake City | 🇺🇸 United States | |
| 2 | San Diego | 🇺🇸 United States | |
| 3 | San Francisco | 🇺🇸 United States | |
| 4 | Portland | 🇺🇸 United States | |
| 5 | Los Angeles | 🇺🇸 United States |
With luck
About 10% of wildlife watchers report a California Root Borer sighting in Sequoia and Kings Canyon National Parks on a given day, based on 24 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 24th most-seen of the 161 insects we can rate there. Over three days the chance rises to about 40%, and over a week to about 70%, if each day is a fresh chance.
May to July
In those months about 20% of wildlife watchers report a California Root Borer in Sequoia and Kings Canyon National Parks on a given day, against under 5% in September to April, the lowest months. Those are among Sequoia and Kings Canyon National Parks's driest months, with about 30 mm of rain a month against 190 mm in January.
Between 8 and 11 pm
Across all the parks we cover, that three-hour window holds the most California Root Borer sightings with a recorded time, and about 7 in 10 of them come between 6 pm and 6 am: it is mostly seen at night.
Yes
Of the 4 parks where we can rate California Root Borer sightings, Sequoia and Kings Canyon National Parks has the highest daily chance: about 10%. Next come Yosemite National Park (United States, about 10%) and Channel Islands National Park (United States, about 10%).
Same family: Cerambycidae
The closest relatives of the California Root Borer that you can see in Sequoia and Kings Canyon National Parks (family Cerambycidae, Longhorn Beetles) are White-Spotted Sawyer (about 40%), Judolia instabilis (about 10%) and Dimorphic Flower Longhorn Beetle (about 10%), with each one's daily chance of a sighting.
GBIF citizen-science records
It is estimated from how often the California Root Borer is recorded against all the insects logged in Sequoia and Kings Canyon National Parks (24 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.
