Unknown Larva probably Longtailed Sawfly Larva

Subject: unknown insect
Location: Bay Area, California
June 14, 2016 2:45 pm
Love this site and use it often! I got this photo from a co-worker and couldn’t identify it with my books or your posts. It was found on a backpack in early June. Is it some kind of horntail larvae?
I think you are out in the field, I look forward to your answer when you return. Thanks for your time!
Signature: Jess
Resource Analyst  | Stewardship
East Bay Regional Park District
Oakland, CA

Unknown Larva
Probably Longtailed Sawfly Larva

Dear Jess,
Thanks for your patience, though we received so much mail while we were away that we will never be able to respond to everything.  This looks nothing like the drawing of a Horntail larva pictured on Bug Eric.  It appears to have an ovipositor, and we are not aware of any larvae that possess an ovipositor.  Like you, we are stumped.  We will write to Eric Eaton to see if he can provide an identification.  For now, we will classify it as a Beetle Grub, but we are not convinced that this the appropriate classification.

Eric Eaton responds
Reminds me of a rat-tailed maggot, except those don’t have legs, which this one clearly does, plus a head capsule….I’m stumped, too.

Update:  As we await additional information from Jess, we are featuring this posting and requesting assistance from our readership.
Dear Jess, please provide us with any additional information, like size.  Also, was this discovery made on a backpack in the field, or was it shortly after an excursion?

Hello Daniel,
Thanks so much for your time on this! My co-worker is off at a conference, and didn’t provide a size. However, using his photograph of the backpack(see the blurry strap?);  it looks to be about 2.5-3 stitches long. I measured the reinforced stitches on my backpack and got approx. 8-10mm. When I first saw it and said it looked like a cricket larva, he said it was “a small cricket-size”. After review of cricket larva (no ovipositor) and rat-tailed maggots, I emailed. Maybe a female after a molt? But no wings….
He was out in the field, likely a grassland in one of our parks: Alameda or Contra Costa Counties of the East Bay.
Thanks to Eric for his time too.
I hope this helps,

Thanks for the information Jess,
Now that this request is back in our consciousness, we had a thought.  It reminds us of a Sawfly Larva, especially some Australian Sawflies, and sure enough, we found a Longtailed Sawfly in our archives that looks nearly exactly like your image.  Here is another image from the Australian Museum.  Now our mission is to see if any North American Sawflies have the long tail or if this might perhaps be an Australian introduction, a direction in which we are leaning as there are so many eucalyptus trees and other Australian fauna already naturalized in Southern California.  Now, going back to your original request, you suggested a Horntail Larva, and interestingly, Horntails and Sawflies are classified together as Symphyta which you may verify on BugGuide.

Leave a Comment