Members of the family Lucanidae are commonly called stag beetles. There are roughly 1,500 species known; most are found in Asia. Five species are encountered in central Illinois; some very infrequently.
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For those who wish to know more about stag beetles (their classification and distribution), we recommend the University of Nebraska State Museum Guide to the New World Scarab Beetles and the pages associated with the family Lucanidae. [This link will open in a new browser tab.]
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Ceruchus piceus (Weber, 1801). Less than 20 species are known in the genus Ceruchus. Three species are found in North America. One is known from central Illinois. This specimen was collected in Peoria Co., Illinois a number of years ago. These insects are sometimes attracted to lights at night.
Lucanus capreolus (Linnaeus, 1763). This beetle species sometimes is attracted to light at night. Larvae feed on the inner wood of old trees. There is pronounced sexual dimorphism with the males being larger and they posess much larger jaws. This specimen was collected by Mark DuBois in Peoria Co., Illinois. There are less than 60 species in the genus Lucanus; 4 are found in North America (3 of those in central Illinois).
Lucanus elaphus Fabricius, 1775 [male]. This beetle species is more commonly encountered in southern Illinois; the specimen photographed was collected in Union Co., Illinois. The common name for this species is giant stag beetle. As you can see, the mandibles on the male are significanlty larger that the more commonly encountered species of Illinois stag beetle. There is a collection record (by Jeff Prill) from Peoria Co., Illinois (which is why this species has been included here).
Lucanus elaphus [female]. Sexual dimorphism is quite obvious with this species. The female shown here lacks the prominent mandibles which easily distinguish the male from related species. This individual was collected in Johnson Co., Illinois a number of years ago.
Lucanus placidus Say, 1825. This species is distinguished from the related Lucanus capreolus as adults are much darker (often approaching black). Adults are often found in or near rotting wood (as the larvae feed on this). Adults often feed on sap and may be attracted to light at night. This specimen was collected in Mason Co., Illinois.
Platycerus quercus (Weber, 1801). This species has been previously (and consistently) mis-identified as Platycerus virescens. Smith & Paulsen corrected this error in 2017. The common name is oak stag beetle. It has been infrequently encountered in central Illinois. This specimen was collected in McDonough Co., Illinois many years ago.