What a Sawfly Larva! - Observation of the Week, 7/6/21

Our Observation of the Week is this Trichiosoma triangulum sawfly larva, seen in the United States by @masonmaron

“At first, I tended to use iNaturalist to keep count of the species I was seeing, uploading just about every bird I photographed (and photographing every bird I saw),” says Mason Maron.

However, interactions with iNaturalist as a whole and other members of the community led me to start using the site differently, aiming to photograph species I hadn't paid much attention to before, especially those difficult to ID. It was a lot of fun, working with users like @afid to learn more about tracking down orchids and @aispinsects to learn about identifying flies. I definitely started paying more attention to species I had otherwise been ignoring, and began to derive a lot more fun from both iNaturalist and being a naturalist.

So when he recently visited an area near his house, Mason started to look up at the trees around him and noticed lots of holes in their leaves. 

At that moment, I realized that I had always been ignoring those holes, and had never really stopped to think about what was making them. From that day on, I decided to regularly check the leaves in the area when walking through it.

He found several species, including the impressive larva you see above. 

I immediately recognized it as a sawfly, but I was unsure of the species. However, I was pretty sure the distinct, orangey-red marks on the head would probably help me get an ID. I moved the leaf it was munching on around a bit, and it didn't seem to mind at all, so I took the opportunity to get my macro camera nice and close for a clear, clean shot of the head. Of course, the photo looking nice was a positive, too. I then took some other photos of the body for reference and scale, and left the little guy to keep eating away.

He posted the photos on the unofficial iNat Discord Group and, with the help of @giantcicada, was able to identify it to species. 

Sawflies (Suborder Symphyta) are so named because adult females have a distinct saw-like ovipositor, which they use to cut into plant hosts and then lay their eggs. The larvae of most species are herbivorous, and species in this genus like to munch on alders, ash, birch, elm, and, like this one, willow. Adults can often be distinguished from other hymenopterans as they usually lack the tiny connector between their thorax and abdomen, which you usually see in wasps, bees, and ants. Adult Trichiosoma triangulum grow to about 2.5 cm in length and have clubbed antennae.

Now an undergraduate at Washington State University [Go Cougs! As my mother, a proud Wazzu alumna, would want me to say - Tony], Mason (above) is majoring in Wildlife Ecology (he previously wanted to go into engineering, before getting into birds in 2018 - which is also when he joined iNat).

Now, my interests have expanded far beyond birds (though I still give them high priority). I spend most of my summer nights at my moth sheet, photographing the moths, beetles, and any other visitors I get. I have taken a strong interest in a lot of insects, as well as marine biology, which I hope to pursue an education in later down the line. At my university, I am currently prioritizing my own research project, which was fully funded by one of its labs, where I am collecting, assessing, and identifying ectoparasitic lice on Buteo hawks, including some potentially undescribed species.

Photo of Mason taken by Neil Paprocki, whose research Mason was aiding.

- check out the quite different elm zigzag sawfly larva, which was a previous Observation of the Week!

- and really, why saw into plants with your ovipositor when you can just drill?

Posted by tiwane tiwane, July 06, 2021 21:08


Great shot! You’ve got a keen eye.

Posted by lisa_bennett 4 months ago (Flag)

Nice shots!!! Congrats!

Posted by ken-potter 4 months ago (Flag)

Nice Rough-legged...the hawk, not the sawfly. ;-)

Posted by gcwarbler 4 months ago (Flag)

Congrats Mason! Beautiful shots

Posted by ratite 4 months ago (Flag)

Cool observation; great image!

Posted by seaheart88 4 months ago (Flag)

Really great shots Mason. You seem to be a really first-rate naturalist!

I saw a lot of sawfly larvae last year on a pine tree. They had all- red heads:


Posted by susanhewitt 4 months ago (Flag)

Great observation, congratulations!

Posted by nelson_wisnik 4 months ago (Flag)

Great shot - we spotted sawfly larva for the first time this weekend too!

Posted by juliawattsmeadow 4 months ago (Flag)

Very beautiful pictures.

Posted by hermanberteler 4 months ago (Flag)


Posted by bernieenglish 4 months ago (Flag)

Awesome shot! Kudos!!

Posted by walkingstick2 4 months ago (Flag)

Congrats Mason!

Posted by birderboy2015 4 months ago (Flag)

Great photos of a very interesting-looking species!
I enjoyed checking out the insect collection at WSU when I was a student there and now I'm wondering if they have a specimen of this sawfly species there.

Posted by whaichi 4 months ago (Flag)

Aw that is a very cute sawfly larva.

Posted by victoriajburton 4 months ago (Flag)

Very cool, Mason!

Posted by robinellison 4 months ago (Flag)

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