4 spp. (in 2 subgenera) in our area(1)
; 3 subgenera total(2)
H. ensifer: s. Florida; Caribbean and Mexico to Argentina
H. insularis: s. AZ, s. TX, FL; Mexico to Central America
H. triangularis: widespread in 48 states, southern Canada (BC-QC); Mexico
H. ovatus: eastern US, se. Canada; (QC-FL-TX-IA); Mexico
the largest members of the family, >30 mm (our spp. up to 40 mm, extralimital spp. up to ~50 mm)(2)(3)
key to spp. in Epler (2010)(2)
and Short & McIntosh (2014)(4)
widespread N. Amer. & Eurasia(1)(3)
stagnant/slow waters; prefer deeper water (weedy ponds, deep drainage ditches)(2)
Female deposits up to 140 yellow eggs in cocoon-like egg case with a "mast". Case is large, about 15 X 24 mm, and floats or is attached to an underwater object. Larvae aquatic, predatory? Pupation occurs in moist soil. Adults emerge in under two weeks and return to the water. There are one or two generations per year. Some adults overwinter on land, under leaf litter. Others may remain under ice of ponds and stay active all winter. Lifespan may exceed one year.
The subgenus Dibolocelus in Mexico was recently revised, with five additional species (other than H. ovatus) recorded along the Gulf of Mexico coast in Mexico and one in Cuba. Further study could reveal the presence of these species in southern Texas or Florida. See Arce-Pérez et al. 2021.
Short, A. E. Z., and McIntosh, C. E. 2014. Review of the Giant Water Scavenger Beetle Genus Hydrophilus
Geoffroy (Coleoptera: Hydrophilidae) of the United States and Canada. The Coleopterists Bulletin 68(2): 187–198. http://www.bioone.org/doi/full/10.1649/0010-065X-68.2.187
Arce-Pérez, Roberto; Arriaga-Varela, Emmanuel; Novelo-Gutiérrez, Rodolfo; Navarrete-Heredia, Josè L. (2021). Giant water scavenger beetles Hydrophilus subgenus Dibolocelus (Coleoptera: Hydrophilidae) from Mexico with description of two new species
. Zootaxa. 5027 (3): 387–407.