Explanation of Names
Agabus Leach, 1817
Agabus was an early follower and prophet of Christianity during the 1st century AD. (Wikipedia
Large and diverse holarctic genus; North America: 106 species (1)
Eyes notched at antennal bases
Row of setae present on the ventral posterior apical angle (point where tibia and femur meet) of the hind femur
Hind tarsal claws subequal in length (compared to unequal claws in Ilybius)
Males can be separated from females by the broadly expanded front tarsi, which also bear numerous adhesive setae.
Species identification is often difficult given the large number of species in the genus and close similarities in appearance between species. However, there are a few exceptions that can be easily identified by colour alone. Examination of male specimens is often most reliable for species ID.
Larvae: similar in appearance to Ilybius larvae
2 whorls of hair on cerci (urogomphi) with or without secondary setae
lateral sides of the head without horizontal keel; row of lateral head spines do not meet the eye but run in an oblique angle below it (unlike Ilybius)
Various freshwater habitats- from vegetation-rich permanent ponds to lotic environments (streams and rivers); some also occur in temporary pools, others inhabit barren, mineral-rich aquatic environs in the arctic and alpine zones (1)
Both adults and larvae are predaceous on smaller aquatic insects
Various; most have been reported to overwinter as adults with breeding, egg laying and immature stages occuring in spring and summer but others may overwinter as larvae and/or eggs. (1)
For keys, full descriptions of biology and ecology, and range information for all known North American Agabus species see:
Larson DJ, Y. Alarie, and RE Roughley. 2000. Predaceous Diving Beetles (Coleoptera: Dysticidae) of the Nearctic Region, with emphasis on the fauna of Canada and Alaska. pp. 481-694.
: Excellent images of pinned specimens representing 33 species
Discover Life in America
: images and descriptions of several species