November 5, 2009
A co-worker of mine knows a little bit about my fascination with beetles, bugs, spiders and insects.  The other day, he was arriving for day shift as I left from my night shift, and said “Wait, I found you something!”  It turns out it was this guy, a black shiny hard shelled beetle almost an inch-and-a-half long.
He was found early Halloween morning, on the street in Norwich, CT, pretty far from any water, but shortly after some heavy overnight rains.  Perhaps he was washed out of a pond or creek.
It appears to be a Dyticid – Cybister fimbriolatus
according to Bug Guide:
I put him in a large shallow container of water that was in my yard, neglected most of the fall and looked like it had some other small critters in it.  He was a strong swimmer, head down and tail up the whole time.  The back legs are hairy and very long, and seem to be used much in the way a frog swims.  The hairs act a bit like a frog’s webbed feet.  He was never aggressive and appears to have very small mouth parts, and large bluish eyes.
I placed a quarter with him so you can get a sense of his size.  In Connecticut, we don’t see a lot of bugs this late in the year, so I hope he has found a good place to spend the winter.  We haven’t had a hard frost yet being near the coast so hopefully he will locate a good hiding spot.
Rob Bareiss,
New London, CT

Giant Diving Beetle

Giant Diving Beetle

Hi Rob,
We were a bit busy when your letter arrived, and it was overlooked.  We agree that this is a Predaceous Diving Beetle in the family Dytiscidae and we are posting your wonderful letter and photo a few months late.

Hey that’s cool!  I’m glad you guys liked the pictures and that I was
right with the identification.  I’m still new to this but your site has sparked
a revival of an interest that I have had for over 35 years!
Take care and Happy New Year,

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3 Responses to Predaceous Diving Beetle

  1. mardikavana says:

    I don’t think that this is a Cybister but some kind of a Dytiscus male. The yellow stripe is too wide. Cybisters are flatter and and the tip of Cybister is sharp.

  2. sankar says:

    I want to know in details of the biology of the Cybister species atleast the Indian species.
    I am rearing them in crude way and moving with a great scarcity of Taxonomist in this field.
    i have photographs but I don’t know the method of uploading it here.

  3. Carl Potter says:

    Just Found one one my Lawn in Quinte West Ontario

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