Thecesternus affinis

LeConte, 1857

Thecesternus affinis is a small, flightless weevil in the Curculionidae, native to North America. It belongs to a of seven collectively known as 'bison dung weevils' or 'bison snout beetles' due to their historical association with seeking shelter under bison on the plains. The species is , cryptic, and exhibits death-feigning when disturbed. It is poorly studied compared to its T. hirsutus, which was evaluated as a agent.

Pronunciation

How to pronounce Thecesternus affinis: /θɛˈsɛstərnəs əˈfaɪnɪs/

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Identification

are approximately 6 mm in body length with a notably truncated, short rostrum ('nose') compared to many other weevils. When threatened, they draw in their , , and legs to feign death, making them difficult to observe with appendages extended. The is flightless. -level identification within Thecesternus requires examination of specific morphological characters not detailed in available sources; the genus is characterized by the short rostrum and compact body form.

Habitat

Found in central, eastern, and southwestern United States and southern Canada. Historical included plains environments where bison provided shelter from daytime heat. In modern times, likely occupies disturbed and open habitats with suitable ground cover for shelter. In Colorado, have been found on sidewalks and in Black Forest area.

Distribution

North America: central, eastern, and southwestern United States north to Alberta, Canada. Specific records include Alberta, British Columbia, and Saskatchewan in Canada. The collectively ranges across this region; individual distributions within the genus are less precisely documented.

Seasonality

active above ground during summer months. In Colorado, adults have been observed in April. likely involves winter larval dormancy with adult in spring, based on T. hirsutus .

Behavior

and flightless. Seeks shelter during daytime heat, historically under bison . Exhibits death-feigning () when disturbed, retracting , , and legs. Highly sensitive to motion, vibration, and light, making observation of extended appendages difficult.

Sources and further reading