Geotrupes semiopacus

Geotrupes semiopacus can be distinguished from the similar and sympatric G. blackburnii by its slightly larger size and the presence of obvious punctures in the lateral areas of the pronotum (G. blackburnii has a nearly impunctate pronotum). It differs from G. splendidus in coloration; G. splendidus typically exhibits bright green, yellow-green, golden, reddish, or dark purple coloration with punctured elytral striae and sutural striae ending at the scutellum. Reliable identification of G. semiopacus may require examination of subtle morphological characters and geographic context.

Deciduous and mixed woodlands, particularly high-quality forested areas with intact ground layer vegetation. Adults are found on forest trails and in forested areas with sufficient mammal activity to provide dung resources. The species occurs in dry-mesic to mesic upland forests and riparian corridors within woodland systems.

Nearctic region: Canada (Manitoba, Ontario, Quebec) and United States (Connecticut, Illinois, Indiana, Iowa, Kansas, Maine, Maryland, Massachusetts, Michigan, Minnesota, Missouri, Nebraska, New Hampshire, New Jersey, New York, North Carolina, North Dakota, Ohio, Pennsylvania, South Dakota, Tennessee, Texas, Vermont, Virginia, West Virginia, Wisconsin). The species shows a broad eastern and central North American distribution.

Adults are active from October through early winter, emerging in late fall, overwintering, and mating in spring. Peak observational records cluster in late October and November prior to sustained freezing conditions.

Adults feed on mammal dung and have been observed utilizing dung for larval development. Like other Geotrupes species, adults may also feed on fungus and leaf litter, though the relative importance of these food sources versus dung for G. semiopacus specifically has not been documented.

• Mammalia (various species) - dung providerMammal dung serves as food source for adults and larval development substrate

Adults emerge in late fall (October), overwinter, and mate in spring. Larvae develop in burrows constructed in soil, provisioned with packed leaf litter or dung. Specific details of egg-laying, larval instars, and pupation for this species have not been documented.

Adults are observed singly on animal dung or on the ground nearby. They exhibit the characteristic earth-boring behavior of the family, constructing burrows in soil for larval provisioning. Activity is concentrated in mild weather conditions during late fall.

Contributes to nutrient cycling through burial and processing of mammal dung and forest floor organic matter. As a member of the Geotrupidae, it facilitates decomposition and soil aeration through burrowing activities. The species serves as a food source for other organisms in forest ecosystems.

Of interest to entomologists and naturalists studying scarab beetle diversity and d beetle ecology. The species has been documented in conservation areas and natural history surveys. No significant economic or agricultural impacts are recorded.

• Geotrupes blackburniiSympatric in Missouri and surrounding regions; differs by smaller size and nearly impunctate pronotum versus punctate pronotum in G. semiopacus
• Geotrupes splendidusOverlapping range and seasonality; distinguished by bright green, yellow-green, golden, reddish, or dark purple coloration and specific elytral striation patterns

• beetle
• scarab
• dung beetle
• forest
• fall active
• North America

• BugGuide
• Wikipedia
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
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