If you’re always looking up to find the birds in the trees, you might miss something interesting on the ground by your feet. And indeed, I almost stepped on this huge 2- inch long Elm Sawfly that really isn’t a fly at all.
One might wonder why a bee would be called a fly — and there isn’t any logical explanation except that the female uses her ovipositor (at the end of the abdomen) like a saw to open cavities in an elm leaf in which she lays about a dozen eggs. Then she moves onto other leaves and does the same thing, until she has deposited about 150 eggs. Whitish larvae hatch out and like all sawflies, immediately begin consuming the vegetation, growing about two inches in a month of eating, until they return to the soil to pupate over the winter. An infestation of sawflies on a young tree may defoliate it so much that the tree becomes stunted, or even dies.
These insects are probably not very numerous in this part of Minnesota since Dutch Elm disease has wiped out so many of their potential host plants. In addition, both the eggs and the larvae may be parasitized by small wasps and never make it to the pupal stage. If they reach the pupal stage in the soil, they may be preyed upon by shrews and deer mice, so seeing one just sitting on the trail might be a rare event.
What a cool insect, Sue. I’ve never anything like that before. There are so many bee mimics, why not have a fly mimic? 🙂
Right! And like a fly (and unlike a bee), it has no stinger.
Very nice Sue! Great images! I do not think I have seen one before. Or maybe I did and thought it was a fly!
I had not heard of sawflies before, but now recognize that a different variety of them from this giganto one has been defoliating my azaleas every spring. Now they have moved on to the gooseberries, but I wised up and dusted them with some powder before they completed the job. They are eating machines — double their length every couple of days!
This a completely new to me. Thanks for all the info and great images. Sounds like a rare find.
I nearly stepped on a 6’ bull snake today.
Now that would be scary…or are you used to them.
Kinda used to them, though I don’t see them often. Once I had a carpet cleaning guy come to my house and when I told him to come in through the screen door he asked, “Is this your pet snake?” A huge bull snake had slide in under the door and curled up in the entryway!
Since I haven’t paid that much attention to the differences between flies and bees I now know what differences to look for. Thanks for the tips. I am having bees, flies and butterflies return to my gardens now. What a wonderful sight to see.
Yes, it is! I love the way the landscape comes back to life each spring.