A Backyard Lifer: the Squash Vine Borer Moth

Squash Vine Borer Moth

Squash Vine Borer Moth

I haven’t been spending as much time in the backyard this summer, mostly because of how hot it has been – I find I have less tolerance for the heat and humidity than I once did. Still, I do check the insects buzzing around my flowers in case anything interesting turns up – perhaps a new lady beetle or hover fly, or an interesting bee or wasp. There hasn’t been much.

Today when I went out to refill the feeders and clean my bird bath I saw something very unusual buzzing around my white Swamp Milkweed flowers – a large bug with fuzzy red legs that often hovered over the blossoms to feed. I wasn’t sure what it was at first, until I downloaded my photos and recognized it as a moth when I saw the antennae and the outline of the wings in my photos. Only then did I realize it was one of the clearwing moths. I tried Googling “clearwing moth with fuzzy red legs” but this only brought up hummingbird moths as a result. It wasn’t until I uploaded my photos to iNaturalist that it was identified as a Squash Vine Borer moth (Melittia cucurbitae).

The Squash Vine Borer is a diurnal species of clearwing moth belonging to the Subfamily Sesiinae. Its larvae feed on squash, pumpkin, melons and zucchini; as such it is considered a pest. It has a wingspan of 28-32 mm and is considered a wasp mimic, though it looks like no wasp I’ve ever seen with its fascinating metallic blue and red body. The feathered antennae shown here identify it as a male.

Squash Vine Borer Moth

Squash Vine Borer Moth

According to my Peterson field guide, these moths are inconspicuous and difficult to find – they do not come to lights as many other moth species do. They fly mostly in June and July.

It was the bright red fuzzy legs that truly captivated me, as well as the distinct black, blue and red colouration. You can see the clear wings here:

Squash Vine Borer Moth

Squash Vine Borer Moth

It was fun to watch, even if I didn’t know what it was at the time; I took as many pictures as I could while it was still present. So far this has been the most interesting bug to visit my Swamp Milkweed since I planted it one year ago!

Squash Vine Borer Moth

The only other bug of interest was a Great Golden Digger Wasp; these are far less common in my yard than their black counterparts, the Great Black Digger Wasp.

Great Golden Digger Moth

Great Golden Digger Moth

It was great to see these fascinating insects visiting my yard, and it made me regret not spending more time out in my own yard this summer to see what else was might have stopped by. I’m just lucky (and very happy!) that the one day I did go out I got a new moth for my both my yard list and my life list!

2 thoughts on “A Backyard Lifer: the Squash Vine Borer Moth

  1. I first saw one of these in 2016, and I was thrilled to see this pretty moth. Until I identified it, and realized that all our squashes, cukes, melons and zukes were now in serious peril. I found about a hundred eggs scattered around in the days after, and have had little luck growing any of these plants since, sadly. It’s a dayflier, so I’m not surprised it doesn’t come to lights, though I didn’t know that.

    I caught sight of a great golden digger wasp in my garden a couple of times this summer, but didn’t manage to photograph them. Did see them on Île Dorval, and along the Ottawa River Parkway, and photographed them there. I did have a couple of very striking great black digger wasps visit, and they absolutely loved oregano blooms, and really nothing else. What do they like in your garden?

    • Hi Alison, so far they seem to like my Bee Balm and Swamp Milkweed. I don’t think I’ve seen them on my Purple Coneflower which is the other pollinator plant in bloom.

      I actually don’t have much in my garden this year as we took out the “sun” garden bed when a portion of our fence fell over in a windstorm a year ago. Due to Covid and the rising cost of materials we had to put off fixing it until next year. I’m hoping to put some asters in as they are also insect magnets!

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