Introduction. The name of each listed species is followed by up to five sources that report the species as occurring in Michigan. Sources in all upper-case letters refer to specific insect collections: MSU-ARC refers to material held by the Michigan State University Arthropod Research Collection (data provided by G. Parsons). All others refer to collection data extracted from the Symbiota Collections of Arthropods Network (SCAN) database online at https://scan-bugs.org/. See the Methods page for a list of abbreviations and associated collections.

Species names preceded by a single '?' are considered probable (for occurring in Michigan) but uncertain records. Those preceded by '??' are considered possible but unlikely to occur in Michigan. Species that are fully accepted as having valid Michigan records are unmarked. Species reported in the literature that we consider to be erroneous Michigan records are in a separate list following the others.

HYDROPHILIDAE

3 subfamilies, 8 tribes, 21 genera, 82 species

Subfamily Chaetarthriinae

Chaetarthria atra (LeConte, 1863): Haack and Ruesink (2020), Miller (1974), MSU-ARC

Chaetarthria pallida (LeConte, 1861): Miller (1974), Willson (1970), Bright (2015), Hubbard and Schwarz (1878), MSU-ARC

Subfamily Hydrophilinae

Tribe Anacaenini

Anacaena lutescens (Stephens, 1829): Haack and Ruesink (2020), Bright (2015), LeConte (1878), Hubbard and Schwarz (1878), MSU-ARC; authorities disagree on whether what we have in MI is A. lutescens, A. limbata (Fabricius) or an undescribed species very similar to these two.

Crenitis digesta (LeConte, 1855): Bright (2015), Wolcott (1909), Hubbard and Schwarz (1878), MSU-ARC

Paracymus confluens Wooldridge, 1966: Wooldridge (1966), Smetana (1988), Bright (2015), Downie and Arnett (1996), MSU-ARC

?Paracymus confusus Wooldridge, 1966: Bright (2015), Downie and Arnett (1996); Willson (1970) says this sp. not recorded from MI

Paracymus despectus (LeConte, 1863): Wooldridge (1966), Bright (2015), Hatch (1924), Downie and Arnett (1996), MSU-ARC

Paracymus subcupreus (Say, 1825): Bright (2015), Hatch (1924), Andrews (1923), Hubbard and Schwarz (1878), MSU-ARC; very common throughout MI (Willson, 1970)

Tribe Berosini

Berosus aculeatus LeConte, 1855: Smetana (1988), Bright (2015), Downie and Arnett (1996), MSU-ARC

Berosus fraternus LeConte, 1855: Bright (2015), Downie and Arnett (1996), MSU-ARC

?Berosus infuscatus LeConte, 1855: Bright (2015), Andrews (1916), Andrews (1923), FMNH:FMNHINS; Charity Island specimens in UMMZ:UMMZI & SI:NMNH; however, a southern sp. that should not occur in MI

Berosus peregrinus (Herbst, 1797): Bright (2015), Schwarz (1876), Hatch (1924), Downie and Arnett (1996), MSU-ARC

Berosus sayi Hansen, 1999: Bright (2015), Andrews (1923), Downie and Arnett (1996), Hubbard and Schwarz (1878), MSU-ARC

Berosus stylifer Horn, 1873: Smetana (1988), Bright (2015), MSU-ARC

Tribe Hydrobiusini

Sperchopsis tessellata (Ziegler, 1844): Bright (2015), Spangler (1961), Andrews (1923), Hubbard and Schwarz (1878), MSU-ARC

Tribe Hydrophilini

Cymbiodyta acuminata Fall, 1924: Smetana (1974), Willson (1970), Bright (2015), MSU-ARC

Cymbiodyta blanchardi Horn, 1890: Willson (1970), Andrews (1916), Hatch (1924), Bright (2015), MSU-ARC

Cymbiodyta chamberlaini Smetana, 1974: Smetana (1974), Smetana (1988), Bright (2015), Downie and Arnett (1996)

Cymbiodyta minima Notman, 1919: Smetana (1974), Willson (1970), Bright (2015), Downie and Arnett (1996), MSU-ARC

Cymbiodyta semistriata (Zimmermann, 1869): Smetana (1974), Bright (2015), Downie and Arnett (1996)

Cymbiodyta toddi Spangler, 1966: Smetana (1974), Bright (2015), Willson (1970), Downie and Arnett (1996), MSU-ARC

Cymbiodyta vindicata Fall, 1924: Smetana (1974), Bright (2015), Willson (1970), Downie and Arnett (1996), MSU-ARC

?Enochrus blatchleyi (Fall, 1924): Bright (2015), Downie and Arnett (1996); MI record needs confirmation

Enochrus cinctus (Say, 1824): Gunderson (1978), Bright (2015), Andrews (1916), Hubbard and Schwarz (1878), MSU-ARC

Enochrus consors (LeConte, 1863): Gunderson (1978), Willson (1970), Bright (2015), Schwarz (1876), Hubbard and Schwarz (1878); uncommon

Enochrus consortus Green, 1946: Gunderson (1978), Willson (1970), Bright (2015), Downie and Arnett (1996), MSU-ARC

Enochrus diffusus (LeConte, 1855): Bright (2015), Ruesink and Parsons (2023), MSU-ARC; mostly a western sp., very scarce in the east

Enochrus fimbriatus (Melsheimer, 1844): Gunderson (1978), Andrews (1923), Hubbard and Schwarz (1878), Bright (2015), MSU-ARC

Enochrus hamiltoni (Horn, 1890): Gunderson (1978), Bright (2015), Andrews (1916), Downie and Arnett (1996), MSU-ARC; one of the MSU specimens is from Andrews Charity Island collection & was misidentified by him as Cymbiota blanchardi

Enochrus ochraceus (Melsheimer, 1844): Haack and Ruesink (2020), Gunderson (1978), Bright (2015), Hubbard and Schwarz (1878), MSU-ARC; extremely common throughout MI (Willson, 1970)

Enochrus pygmaeus nebulosus (Say, 1824): Gunderson (1978), Bright (2015), Hatch (1924), Hubbard and Schwarz (1878), MSU-ARC

Enochrus sayi Gundersen, 1977: Gunderson (1978), Bright (2015), Downie and Arnett (1996), MSU-ARC

Helocombus bifidus (LeConte, 1855): Haack and Ruesink (2020), Bright (2015), Willson (1970),Hubbard and Schwarz (1878), MSU-ARC

Hydrobius fuscipes (Linnaeus, 1758): Haack and Ruesink (2020), Bright (2015), Downie and Arnett (1996), Hubbard and Schwarz (1878), MSU-ARC; extremely common throughout MI (Willson, 1970)

Hydrochara obtusata (Say, 1823): Smetana (1980), Bright (2015), Downie and Arnett (1996), Willson (1970), Hubbard and Schwarz (1878), MSU-ARC

Hydrochara simula Hilsenhoff & Tracy, 1982: Hilsenhoff and Tracy (1982), Bright (2015), Downie and Arnett (1996)

Hydrochara soror Smetana, 1980: Smetana (1980), Bright (2015), Downie and Arnett (1996), MSU-ARC

Hydrophilus ovatus Gemminger & Harold, 1868: Short and McIntosh (2014), Bright (2015), Peck and Thomas (1998), Hubbard and Schwarz (1878), MSU-ARC

Hydrophilus triangularis Say, 1823: Short and McIntosh (2014), Bright (2015), Downie and Arnett (1996), Hubbard and Schwarz (1878), MSU-ARC

Limnohydrobius melaenus (Germar, 1824): Haack and Ruesink (2020), Bright (2015), Downie and Arnett (1996), Hatch (1924), MSU-ARC; used to be in the genus Hydrobius

Tropisternus blatchleyi modestus d'Orchymont, 1938: Willson (1970), Bright (2015), MSU-ARC

Tropisternus columbianus Brown, 1931: Willson (1970), Bright (2015), MSU-ARC

Tropisternus glaber (Herbst, 1797): Willson (1970), Bright (2015), Andrews (1923), Hubbard and Schwarz (1878), MSU-ARC

Tropisternus lateralis nimbatus (Say, 1823): Bright (2015), Andrews (1923), Hubbard and Schwarz (1878), Downie and Arnett (1996), MSU-ARC

Tropisternus mixtus (LeConte, 1855): Willson (1970), Bright (2015), Andrews (1923), Hatch (1924), Hubbard and Schwarz (1878), MSU-ARC; a very common species (Willson, 1970)

Tropisternus natator d'Orchymont, 1938: Willson (1970), Peck and Thomas (1998), Bright (2015), MSU-ARC; common throughout the lower peninsula (Willson, 1970)

Tribe Laccobiini

Laccobius agilis (Randall, 1838): Cheary (1971), Bright (2015), Hatch (1924), Hubbard and Schwarz (1878), MSU-ARC

Laccobius arenarius Cheary, 1971: Cheary (1971), Willson (1970), MSU-ARC

?Laccobius cinereus columbianus Miller, 1965: Downie and Arnett (1996), Bright (2015); needs confirmation

Laccobius minutoides d'Orchymont, 1942: Cheary (1971), Willson (1970), Bright (2015), MSU-ARC

Laccobius nevadensis magnus Cheary, 1971: Cheary (1971)

Laccobius spangleri Cheary, 1971: Cheary (1971), Willson (1970), Bright (2015), MSU-ARC

?Laccobius truncatipennis Miller, 1965: Bright (2015); needs confirmation

Subfamily Sphaeridiinae

Tribe Coelostomatini

Phaenonotum exstriatum (Say, 1835): Smetana (1978), Bezanson and Floate (2019), Willson (1970), Hubbard and Schwarz (1878), MSU-ARC

Tribe Megasternini

Cercyon analis (Paykull, 1798): Smetana (1978), Andrews (1923), Hubbard and Schwarz (1878), MSU-ARC

Cercyon assecla Smetana, 1978: Smetana (1978), Bezanson and Floate (2019), Downie and Arnett (1996)

Cercyon cinctus Smetana, 1978: Smetana (1978), Downie and Arnett (1996)

Cercyon connivens Fall, 1924: Smetana (1978), Downie and Arnett (1996)

Cercyon erraticus Smetana, 1978: Smetana (1978), Downie and Arnett (1996)

Cercyon haemorrhoidalis (Fabricius, 1775): Smetana (1978), Bezanson and Floate (2019), Wassmer (2020), Hubbard and Schwarz (1878), MSU-ARC

Cercyon herceus herceus Smetana, 1978: Smetana (1978)

Cercyon lateralis (Marsham, 1802): Smetana (1978), Bezanson and Floate (2019), Downie and Arnett (1996), MSU-ARC

Cercyon marinus Thomson, 1853: Smetana (1978), Bezanson and Floate (2019), Bright (2015), Downie and Arnett (1996), MSU-ARC

Cercyon mendax Smetana, 1978: Smetana (1978), Bright (2015), Downie and Arnett (1996)

Cercyon minusculus Melsheimer, 1844: Smetana (1978), Bezanson and Floate (2019), Downie and Arnett (1996), MSU-ARC

Cercyon nigriceps (Marsham, 1802): Smetana (1978), Bezanson and Floate (2019), Hubbard and Schwarz (1878), Downie and Arnett (1996), MSU-ARC

Cercyon occallatus (Say, 1825): Smetana (1978), Downie and Arnett (1996), Hubbard and Schwarz (1878), MSU-ARC

Cercyon praetextatus (Say, 1825): Smetana (1978), Bezanson and Floate (2019), Andrews (1923), Hubbard and Schwarz (1878), MSU-ARC

Cercyon pygmaeus (Illiger, 1801): Smetana (1978), Bezanson and Floate (2019), Wassmer (2020), Hatch (1924), MSU-ARC

Cercyon quisquilius (Linnaeus, 1760): Smetana (1978), Bezanson and Floate (2019), Wassmer (2020), Downie and Arnett (1996), MSU-ARC

Cercyon roseni Knisch, 1922: Smetana (1978), Bright (2015), Downie and Arnett (1996)

?Cercyon terminatus (Marsham, 1802): Wassmer (2020); a palearctic sp. previously known from nearby states, MI record needs confirmation

Cercyon unipunctatus (Linnaeus, 1758): Smetana (1978), Bezanson and Floate (2019), Hubbard and Schwarz (1878), Downie and Arnett (1996), MSU-ARC

Cryptopleurum americanum Horn, 1890: Wassmer (2020), Willson (1970), MSU-ARC

Cryptopleurum minutum (Fabricius, 1775): Smetana (1978), Bezanson and Floate (2019), Wassmer (2020), Andrews (1923), MSU-ARC

Cryptopleurum subtile Sharp, 1884: Smetana (1978), Bezanson and Floate (2019), Wassmer (2020), Downie and Arnett (1996)

Cryptopleurum vagans LeConte, 1855: Smetana (1978), Hubbard and Schwarz (1878), Downie and Arnett (1996)

Oosternum pubescens (LeConte, 1855): Willson (1970), MSU-ARC

Tectosternum naviculare (Zimmermann, 1869): Smetana (1978), Hubbard and Schwarz (1878), Downie and Arnett (1996)

Tribe Sphaeridiini

Sphaeridium bipustulatum Fabricius, 1781: Smetana (1978), Bezanson and Floate (2019), Wassmer (2020), Downie and Arnett (1996), MSU-ARC

Sphaeridium lunatum Fabricius, 1792: Smetana (1978), Bezanson and Floate (2019), Wassmer (2020), Downie and Arnett (1996)

Sphaeridium scarabaeoides (Linnaeus, 1758): Smetana (1978), Bezanson and Floate (2019), Wassmer (2020), Andrews (1923), MSU-ARC

The following species were also reported from Michigan, but we consider them to be adventive, misidentifications or other errors:

Subfamily Hydrophilinae

Tribe Hydrophilini

Cymbiodyta rotunda (Say, 1825): Downie and Arnett (1996); an eastern sp.; should not be in MI

Enochrus carinatus fucatus (Horn, 1873): Andrews (1923) as Philhydrus fucatus Horn; this SW sp. does not occur in MI

Helochares maculicollis Mulsant, 1844: Andrews (1916); H. maculicollis is more southern, should not occur in MI; 2 Andrews specimens from Charity Islands in MSU collection IDed as this species are actually Enochrus 

Tropisternus sublaevis (LeConte, 1855): Andrews (1916), Andrews (1923); a southwestern sp. that does not occur in MI, he probably had T. columbianus

Subfamily Sphaeridiinae

Tribe Megasternini

Cryptopleurum crenatum (Kugelann, 1794): Wassmer (2014), Wassmer (2020); a palearctic sp. that Smetana (1978) says does not occur in N.A.

This family list was last updated: December 28, 2022