Cerotoma trifurcata
In 3 days ~10% in a week ~20%
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 Chicago on a given day, based on 23 verified sightings from GBIF citizen-science data. It is the 390th most-seen of the 978 insects we can rate there. Over three days the chance rises to about 10%, and over a week to about 20%, if each day is a fresh chance.
Any time of year
In every month with enough records, under 5% of wildlife watchers report a Bean Leaf Beetle in Chicago on a given day, so our monthly data shows no clear season.
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.
Among the best
Of the 5 cities where we can rate Bean Leaf Beetle sightings, Chicago ranks 2nd at under 5%, level with the leaders once rounded. The best odds are in Montreal (Canada, under 5%).
Same family: Chrysomelidae
The closest relatives of the Bean Leaf Beetle that you can see in Chicago (family Chrysomelidae, Leaf Beetles) are Spotted Cucumber Beetle (about 10%), Swamp Milkweed Leaf Beetle (about 10%) and Dogbane Leaf Beetle (about 10%), 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 Chicago (23 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.
