Cerotoma trifurcata
In 3 days ~10% in a week ~30%
Cerotoma trifurcata (also known as the bean leaf beetle) is a species of beetle in the Chrysomelidae family that can be found in the Eastern and West United States. Previously considered a minor pest, the past 30 years have seen an increase in population abundance. It has spread from its native region of the Mississippi Delta into the American Midwest and Canada. C. trifurcata prefers soybeans as a host, but it has been found on alfalfa, cowpea, snap beans, and cucurbits. It damages crops due to pod damage and being a vector for bean pod mottle virus.
The beetle exhibits overwintering behaviors. Overwintering is associated with mating behavior and regulates when the beetle lays its eggs. Adult beetles are 3.5–5.5 millimeters (0.14–0.22 in) in length, and have a punctuated elytra at their posterior region. Morphs can have colors ranging from light gray to shades of yellow, brown, orange, or red. The elytra has a black triangle in the middle behind the thorax and typically has six additional black spots with a black band around the edges, though non-spotted morphs also occur. The head is always black.
Eggs are orange and spindle shaped,... Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Shenandoah National Park | 🇺🇸 United States |
More parks will be added in future updates.
| # | City | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Montreal | 🇨🇦 Canada | |
| 2 | Chicago | 🇺🇸 United States | |
| 3 | Toronto | 🇨🇦 Canada | |
| 4 | Minneapolis [Saint Paul] | 🇺🇸 United States | |
| 5 | Washington | 🇺🇸 United States |
Rare
Under 5% of wildlife watchers report a Bean Leaf Beetle sighting in Shenandoah National Park on a given day, based on 5 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 630th most-seen of the 723 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.
May, July and October
In those months about 10% of wildlife watchers report a Bean Leaf Beetle in Shenandoah National Park on a given day, against under 5% in June, August–September and November–April, the lowest months.
Between 9 am and noon
Across all the parks we cover, that three-hour window holds the most Bean Leaf Beetle sightings with a recorded time, and about 8 in 10 of them come between 6 am and 6 pm: it is a daytime animal.
Only Shenandoah National Park, in our data
Shenandoah National Park is the only park on Wallace's Line with enough records to rate Bean Leaf Beetle sightings: under 5% of wildlife watchers there report one on a given day.
Same family: Chrysomelidae
The closest relatives of the Bean Leaf Beetle that you can see in Shenandoah National Park (family Chrysomelidae, Leaf Beetles) are Larger Elm Leaf Beetle (about 30%), Dogbane Leaf Beetle (about 20%) and Spotted Cucumber Beetle (about 20%), with each one's daily chance of a sighting.
GBIF citizen-science records
It is estimated from how often the Bean Leaf Beetle is recorded against all the insects logged in Shenandoah National Park (5 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.
