Knowledgebase

Water bug or crustacean…?! #839357

Asked July 06, 2023, 6:11 PM EDT

I saw what looked like a small crab in my irrigation pond, near Bend, OR. Without appendages, it was the size of a quarter or maybe a half dollar. It had two prominent forward appendages. I couldn’t see any others. It was a good swimmer. It swam across the top of the water, maybe, ten feet, leaving a small wake. Then, it settled down ~10 cm underwater, motionless atop a bunch of algae. This is our 13th summer here, and I’ve never seen anything similar. Please help with i.d. Thanks!

Deschutes County Oregon

Expert Response

Hello.  I am consulting with an expert in aquatic invertebrates and will get back to you when I hear from him but it will take some time because I am officially on vacation until July 25.

An Ask Extension Expert Replied July 13, 2023, 11:34 PM EDT

          It's pretty hard to know exactly what that person saw without a photo or a specimen. However, I think that could have been a giant water bug (Hemiptera: Belostomatidae) from the genus Belostoma.

The swimming style could fit and they often have their front legs out facing forward. The other legs might've been tucked under its body, and if that was the case, they might not have been visible.

Here is an example of one of these with the mid and hind legs exposed.

https://bugguide.net/node/view/2255653

That's my best guess based on the description.


Buffalo Belostoma - Belostoma flumineum

An online resource devoted to North American insects, spiders and their kin, offering identification, images, and information.

bugguide.net

An Ask Extension Expert Replied July 16, 2023, 11:58 AM EDT
Thank you so very much! That is definitely what I saw. The front legs (pincers?) are distinctive.

Sent from my iPhone

> On Jul 16, 2023, at 8:58 AM, Ask Extension <ask> wrote:
> 
> Buffalo Belostoma</ask>
The Question Asker Replied July 18, 2023, 1:48 AM EDT

Loading ...