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Subfamily Dytiscinae

Predacious Diving Beetle - Dytiscus carolinus Predaceous Diving Beetle - Acilius mediatus Underwater Beetle? - Acilius Unknown diving beetle - Acilius Aquatic beetle - Hydaticus bimarginatus Unknown beetle - Thermonectus basillaris Thermonectus basillaris T. n. nigrofasciatus - Thermonectus nigrofasciatus
Classification
Kingdom Animalia (Animals)
Phylum Arthropoda (Arthropods)
Subphylum Hexapoda (Hexapods)
Class Insecta (Insects)
Order Coleoptera (Beetles)
Suborder Adephaga
Family Dytiscidae (Predaceous Diving Beetles)
Subfamily Dytiscinae
Numbers
~40 spp. in 6 genera of 4 tribes in our area, >250 spp. in 12 genera of 5 tribes total(1)
Size
8-40 mm (Nearctic species)
Identification
Adults:
Eyes unnotched at antennal bases
scutellum visible
male protarsomeres 1-3 modified to form a broad oval palette, often with suckers on the ventral surface (used to grasp the female during mating)
Larvae:
Anterior margin of the clypeus (frontoclypeus) is rounded
anteroventral margin of femur and tibia with a fringe of swimming hairs
abdominal segments 7 and 8 fringed laterally with swimming hairs
Remarks
These beetles store up toxins as a poisonous milk in the prothoracic glands. Predators are sickened and throw up the beetle. Fish that eat this beetle fall into a narcotic state.(2)
Works Cited
1.A World Catalogue of the Family Dytiscidae, or the Diving Beetles (Coleoptera, Adephaga)
Nilsson and Hajek. 2019. Distributed by authors.
2.Introduction to Ecological Biochemistry
J.B. Harborne. 1993. Academic Press Limited.