What's That Bug? does not endorse extermination

catapillar
Location: west central Wisconsin (USA)
August 4, 2011 7:33 pm
I have a bunch of these worms on a weeping willow tree, what are they & how do I get rid of them? are they dangerous? I have never seen them here before. There are yellow ones & also Pink ones. they look very similar & I suspect they could be males & females. they appear to be eating the tree leaves. We have had warmer then average temps here this year & lots of rain.
Signature: Thanks for any help

Elm Sawfly Larvae

Though they look like caterpillars, these are actually the larvae of Elm Sawflies, Cimbex americana.  Sawflies are related to bees and wasps.  We do not give extermination advice.

Elm Sawfly Larva

What's That Bug? does not endorse extermination
Location: Wisconsin

3 Responses to Elm Sawfly Larvae

  1. Krazy2kats says:

    This is what I think I picked up in the park today. The color, shape and size looks right but there wasn’t any line down the back. Do you have an idea how big these things get? This one was about 2-3″ and was the flesh colored one. Also, it was grabbing me with something on the underside at the back end of it and it had little pinchers by it’s “mouth”. I think the trees in the area are Oaks not Elms. I live in NYC and it has been pretty hot here lately but not much rain but LOTS of Flies and I think they are biting flies, which is very unusual for this area. Could this be what I saw?

    • bugman says:

      Elm Sawflies are frequently confused with caterpillars. Without a photo, it might be difficult to determine what you saw.

  2. John says:

    Luna Moth can take on a pinkish shade before pupating. They look similar at first, about the size of a finger and lack the stripe. TIme of year and food source are in sync with the observation.

    This web page did confirm a mystery I had. I found a larva, felt sure it was a caterpillar but could not find any caterpillars with a strip the full length of the body. Someone suggested Elm Sawfly. From what I read, there is an extra pair of prolegs on the sawfly (6 vs 5) and the head is round. I did not collect the specimen for further observations so have to go from my picture. Your picture is dead on, small yellow bumps and all.

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