Horned Passalus Beetle

Horned Passalus Beetle

Odontotaenius disjunctus

Daily sighting probability ~10% · With luck
at Baltimore

In 3 days ~40% in a week ~70%

132 Verified sightings at Baltimore
186 In all 5 parks From 2019 to 2026
April Best month
☀️ Diurnal When it's spotted

About the Horned Passalus Beetle

Odontotaenius disjunctus, the patent-leather beetle or horned passalus, is a saproxylic beetle in the family Passalidae (bess beetles) which can grow to over 3 cm long, weigh 1-2 grams and are capable of pulling 50 times their own weight. They have been used to study several aspects of general family characteristics since the early 1900s but remain a relatively unknown species within the diverse Coleoptera order.

Odontotaenius disjunctus is most commonly found in climates with higher humidity, mainly in the warmer parts of both hemispheres, and also widely distributed in temperate North American forests. O. disjunctus beetles are usually found under, or inside, old logs or stumps and are rarely observed outside of their wooden habitats.

These beetles can be found in rotting logs, especially of oak and hickory. This specific locale offers unique benefits in regards to protection from predators and external abiotic factors such temperature and precipitation. There is a level of stability with the two factors mentioned, the water retention in the wood helps to keep temperatures stable while aiding in further decomposition of the log itself... Wikipedia →

Global Distribution

Parks Where Found

# Park Country Daily sighting probability
1 Congaree National Park 🇺🇸 United States
~20%
2 Great Smoky Mountains National Park 🇺🇸 United States
~20%
3 Shenandoah National Park 🇺🇸 United States
~10%
4 Point Pelee National Park 🇨🇦 Canada
~10%
5 Merritt Island National Wildlife Refuge 🇺🇸 United States
~10%

Cities Where Found

# City Country Daily sighting probability
1 Washington 🇺🇸 United States
~20%
2 Baltimore 🇺🇸 United States
~10%
3 Philadelphia 🇺🇸 United States
~10%
4 New York City 🇺🇸 United States
~10%
5 Houston 🇺🇸 United States
<5%
6 Dallas 🇺🇸 United States
<5%

Before you go

What are the chances of seeing a Horned Passalus Beetle in Baltimore?

With luck

About 10% of wildlife watchers report a Horned Passalus Beetle sighting in Baltimore on a given day, based on 132 verified sightings from GBIF citizen-science data. It is the 26th most-seen of the 705 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.

When is the best time to see a Horned Passalus Beetle in Baltimore?

April–May and November

In those months about 20% of wildlife watchers report a Horned Passalus Beetle in Baltimore on a given day, against under 5% in January, the lowest month.

What time of day is best to see a Horned Passalus Beetle?

Between 2 and 5 pm

Across all the parks we cover, that three-hour window holds the most Horned Passalus 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.

Is Baltimore the best place to see a Horned Passalus Beetle?

2nd of 6

Of the 6 cities where we can rate Horned Passalus Beetle sightings, Baltimore ranks 2nd at about 10%. The best odds are in Washington (United States, about 20%).

Where does the Horned Passalus Beetle sighting chance come from?

GBIF citizen-science records

It is estimated from how often the Horned Passalus Beetle is recorded against all the insects logged in Baltimore (132 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.

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