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.

This group used to be included as a subfamily within Hydrophilidae.

HYDROCHIDAE

1 genus, 6 species

Hydrochus brevitarsis Knisch, 1922: Smetana (1985), Bright (2015), Downie and Arnett (1996)

??Hydrochus excavatus LeConte, 1855: Andrews (1916); possibly H. neosquamifer Smetana, which was not described until 1988.

??Hydrochus jasodae Makhan, 2002: INHS:INHSIC; a poorly known species, MI records need confirmation

?Hydrochus scabratus Mulsant, 1844: Downie and Arnett (1996), Bright (2015); needs confirmation; Bright cites only Downie and Arnett (1996) as his source

Hydrochus squamifer LeConte, 1855: Hatch (1924), Hubbard and Schwarz (1878), MSU-ARC

Hydrochus subcupreus Randall, 1838: Ruesink and Parsons (2023), MSU-ARC

This family list was last updated: December 28, 2022