Thursday, March 24, 2011


This pretty little black and orange insect is a Sawfly (Dolerus unicolor). Sawflies are not flies at all, but are related to wasps and bees. Even though they are closely related to stinging insects, they cannot sting and are harmless to humans. They get their name "sawfly" from the saw-like ovipositor that the female has, which she uses to deposit eggs inside the stems of plants. This particular species gets its name from the all black male. In the spring these insects are often the first to appear on warm days. I found this one floating on a dead leaf inside one of our cattle tanks. I rescued it and let it dry out. After shaking its wings a few times, it flew off for safer areas.
(Sawfly, shaking her wings to dry them out)

The larvae of sawflies look very much like caterpillars, in fact I have often mistaken them for caterpillars, only to learn via or other resource that I was wrong. The following are some examples of sawfly larvae. Each species of sawfly is usually host specific and will be found on its own particular food choice.

(Found on Elderberry Bush)

(Found on Poison Ivy)

(Found on grasses)

(Found on Elm Tree)

As you can see the diversity of these larva is incredible, and I just love finding them and photographing them. You can also see how very much they look like caterpillars. One key difference Caterpillars can have up to five pairs of abdominal prolegs, but never have more than five pairs. Sawfly larvae always have six or more pairs of abdominal prolegs.

Sawfly Larvae

 Here is a couple of diagrams to help you ID your caterpillar or sawfly larvae.

I can hardly wait until the weather finally warms up and stays warm so I can get outside and look for these wonderfully unique insects.


  1. Wow, who knew. If I was manning the door at a Caterpillars Only Club, I'd let them in. I feel so smart, now, re: # of pairs of prolegs! =)

  2. I agree, they should be called caterpillars. I just love, love, love these babies. I felt pretty smart too when someone set me straight and told me how to tell the difference between the two, LOL

  3. Thanks for posting the pictures and the caterpillar ID info! We found an unusual caterpillar crawling on the snow (!) in February, and were trying to ID it. I think now it was probably not a caterpillar.

  4. you're welcome oldpoet. It took me awhile to learn how to ID the sawfly larvae vs. the caterpillars. I just kept convincing myself that a caterpillar so pretty could not belong to anything other than a butterfly.

  5. Thanks roasted, I am glad you enjoyed it