【22mm】Stenus beetle specimen with large mandibles resembling stag beetle

Scientific Name: Leistotrophus versicolor?

This rove beetle, widely distributed in Central and South America, is known for the extremely developed mandibles of some males.
While many rove beetles that gather around decaying matter seem to prey on the maggots found there, this species appears to prey on adult flies and other insects that gather around dead animals and feces.
Furthermore, among males, some individuals have smaller mandibles and resemble females. It is thought that they employ a survival strategy where they mate with females while larger males mistakenly engage in courtship behavior with them.

Ontholestes gracilis, also known as the Rusty-winged Rove Beetle, is an insect belonging to the family Staphylinidae, distributed from Hokkaido to Kyushu and surrounding islands (Oki, Tsushima). It measures approximately 10-16 mm in length and is characterized by fine mottled patterns. It gathers around tree sap, mushrooms, animal feces, and carrion in mountainous forests and is actively moving. It is particularly common from June to August.

Detailed features and related information are as follows:
Appearance and Characteristics: The name rusty-winged comes from the mottled wings that resemble rust. Like other rove beetles, it has short forewings that conceal long hindwings.
Ecology and Habitat: Found in forests, surrounding mixed forests, and around the sap of sawtooth oaks and mushrooms.
Diet: Feeds on mushrooms and other insects that gather around them.
Caution for Confusion: This species is different from the Paederus fuscipes (commonly known as burn bug), which is venomous. Rusty-winged Rove Beetles typically do not cause serious harm to humans.

We apologize, but we cannot guarantee against downgrading due to shipping.
We will ship the pictured individual collected from Obenteni, Ucayali Province, Peru, at an altitude of 1250m. It was collected in February-March 2022.
My measurement of the head and body length was 22mm.