What looks just like a caterpillar, but isn’t? Sawfly larvae. I’m pretty sure I’ve seen my very first Elm Sawfly larvae (Cimbex americana). I couldn’t help but notice this bright white caterpillar munching on this dark green Elm leaf. I thought I was going to have an awesome entry for The Moth and Me, but sadly, no. When I took a look at this picture, I noticed that I had not seen a caterpillar head quite like this before…usually it is hard to tell where the head is. And if a caterpillar’s head is obvious, it seems like there is never such a prominent eye.

Turns out that this is one of the distinctions between sawfly larvae and caterpillars. Also, caterpillars usually have only 4 pairs of “prolegs,” while sawfly larvae usually have at least five (like this one).1

Want to see what this super-cool, moonlight-white larvae becomes?


Elm Sawfly (Cimbex americana), by Christine Hanrahan, with permission


AAAAWESOME!

  1. Caterpillars of Eastern North America, by David L. Wagner, © 2005 by Princeton University Press

15 Responses to “What Looks Just Like a Caterpillar, But Isn’t?”

  • That is an amazing-looking critter, Amber. Ghostly. I wish it would stay that way – those flies are scaaary.

  • That adult sawfly is one hecka cool beast!

  • Great shots and perfect example of nature’s ability to transform.

    • I can take credit for the larvae pic, but those great pics of the sawfly in its final form were taken by Christine Hanrahan. And they are truly awesome pics…I’m going to be on the look-out for this fly at that same park.

  • This tickled me, Amber. The first time I saw a larva like this (many years ago), I hunted high and low for a moth or butterfly to match it. Good learning experience.

    And the adult? Totally awesome!

    • Hi Jason – I lucked out in my quest for the matching moth or butterfly, by noticing a picture of this sawfly larvae at the beginning of my caterpillar guide – which dumbfounded me by identifying this creature as a fly larvae. Cool! Yes, LOVE the adult…hoping to see one of those big boys!

  • I love the orange antennae on the adult! I’ve just recently starting getting really into insects and I find this sort of critter incredibly cool…

    • Hi Rebecca – interesting to hear what caught your attention about this adult fly. What caught my attention was the way his body is separate from his abdomen, and the size of those thighs. (I am not an entomologist, and I’m sure I just butchered the proper names of the fly’s anatomy…sorry) :-D

  • Deb Lievens:

    I am a moth (+ caterpillar) nut and I had the same experience with the Cimbex. In NH. Took me a while to understand why it wasn’t in Wagner’s great caterpillar guide. Thought it would be so easy to ID. Had to send to Bugguide to get an answer.

    • Wagner anticipated this one, and included a small section in his guide about caterpillars-that-aren’t. This is how I discovered the ID, and bugguide.com cinched it for me. Reminds me, I need to go back to look for the adults!

  • Christine Hanrahan:

    I’m so glad you were able to use the adult sawfly shots. Now, I’d be very happy if I could see the larva!! Your photo is so beautiful. It is a lovely ghostly critter, isn’t it!

  • i actually captured one of these interesting caterpillars with my Canon Rebel T3,..well, what i THOUGHT was one! Thank you so much for clearing up the notion this would be a pretty butterfly or moth! LOL..but, he really looks bad ass though! lol!

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