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Genus Dytiscus

big jawed water bug - Dytiscus Large diving beetle - Dytiscus verticalis - female Dytiscid larva - Dytiscus Diving beetle larva - Dytiscus water beetle - Dytiscus verticalis - female Dytiscus fasciventris - female Diving beetle - Dytiscus Dytiscus fasciventris
Kingdom Animalia (Animals)
Phylum Arthropoda (Arthropods)
Subphylum Hexapoda (Hexapods)
Class Insecta (Insects)
Order Coleoptera (Beetles)
Suborder Adephaga
Family Dytiscidae (Predaceous Diving Beetles)
Subfamily Dytiscinae
Genus Dytiscus
Synonyms and other taxonomic changes
revised in (1)
Explanation of Names
Dytiscus Linnaeus 1758
Greek δυτικός 'able to dive'
12 spp. in our area (10 in Canada), 27 total(2)(3)
adults 22-40 mm, larvae up to 60 mm
Pronotum with or without pale borders. Elytra usually bordered with yellow. Pronotum and/or elytra of female variably smooth or grooved. Metatibiae much longer than broad, outer apical spur very thin. Protarsi of male have two large disks (and small disks) used to grasp female during mating. Hind legs move synchronously while swimming; adults often attracted to light.
Larvae with prominent cerci and dense lateral fringes of hair on the last 2 abdominal segments and cerci. The anterior portion of the head is rounded.

key to spp. in (1)
Holarctic; throughout NA(4)
permanent or temporary freshwater ponds and pools (D. marginicollis may occur in saline ponds), plus streams and rivers; usually found on or among aquatic plants
adults fly from March to November (varies by species)
fish larvae, mosquito larvae, other aquatic invertebrates, sometimes tadpoles and salamanders
Life Cycle
one generation per year; mating occurs in late fall and/or early spring; eggs injected singly into underwater plant stems; fully-grown larvae creep out of water and pupate in moist earth, then emerge as adults in about a week and return to water; overwinters as an adult in permanent waters (D. hybridus may overwinter on land)
See Also
Works Cited
1.A systematic revision of species of Dytiscus Linnaeus (Coleoptera: Dytiscidae). Part 1. Classification based on adult stage
Roughley R.E. 1990. Quaestiones Entomologicae 26: 383-557.
2.A World Catalogue of the Family Dytiscidae, or the Diving Beetles (Coleoptera, Adephaga)
Nilsson and Hajek. 2019. Distributed by authors.
3.Checklist of beetles (Coleoptera) of Canada and Alaska. Second edition
Bousquet Y., Bouchard P., Davies A.E., Sikes D.S. 2013. ZooKeys 360: 1–402.
4.American Beetles, Volume I: Archostemata, Myxophaga, Adephaga, Polyphaga: Staphyliniformia
Arnett, R.H., Jr., and M. C. Thomas. (eds.). 2000. CRC Press LLC, Boca Raton, FL.