What's That Bug? does not endorse extermination

Weird water beetle.. thing..
Location:  Oklahoma City, Oklahoma
August 5, 2010 5:35 pm
Hi, I recently moved to Oklahoma and I’ve already seen many interesting bugs around. We have an above-ground pool in our back yard that had been covered for 6 months and hadn’t been cleaned yet, and after uncovering it, I saw some weird bugs swimming around under the water. I noted the large back legs that it swam with and how it would shoot up to the surface from time to time to get some air, bringing a bubble down with it attached to the behind of it’s abdomen while it searched for food at the bottom of the pool. I caught the largest one I could find in a cup and saw that it looked kinda like a beetle. Can you tell me what the heck this is?
Westin Hacker

Predaceous Diving Beetle

Hi Westin,
This is a Predaceous Diving Beetle in the family Dytiscidae, a family well represented on BugGuide.  Perhaps one of our readers can provide more specific information regarding the genus or species.

Predaceous Diving Beetle

One of our regular contributors, mardikavana, has supplied us with the species name of Cybister fimbriolatus, the Giant Diving Beetle.  According to BugGuide its range is  “Eastern and central North America: from Nova Scotia south to Florida, west to North Dakota, Texas”  and its habitat is “Aquatic: ponds, usually deep water. Comes to lights.

What's That Bug? does not endorse extermination

4 Responses to Giant Diving Beetle

  1. mardikavana says:

    This id definitely a Cybister. Males have modified protarsus, used for grasping female during mating but it’s little bit hard to see the front legs so I can not tell whether it is male or female. But the species should be Cybister fimbriolatus.

  2. zach bruder says:

    Hey Weston, if incase you still come across these Cybister Fimbriolatus, would you be willing to ship 1 or 2 of them to me in California?

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