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Wednesday, 11 September 2019

Striped Pajamas


Helophilus pendulus
We've had an extraordinary number of hoverflies in the garden this year: what seems like hundreds and hundreds of many dozens of species. They're proving quite challenging to actually identify, principally because when I look them up, it turns out I've taken the picture from the wrong angle, or there's some bit of vegetation covering an important ID feature, or the fly is just a little too far away, or some other equally frustrating development. This time, though, I have enough of the "right bits" to identify this particular hoverfly. It's Helophilus pendulus, a common and widespread species found right across Britain and Ireland. It flies from April to November, with numbers peaking in July. I found a couple of them today — one feeding on a Common Cat's-Ear flower, the other sitting quietly on a bit of log in our tiny pond (in reality an upside-down garbage pail lid buried in the grass).  The photo above is from earlier in the summer, when I found another individual resting near the same pond. This species is often found near shallow water, where its larvae, widely known as "rat-tailed maggots", live among decaying vegetation.

The striped thorax of this species is pretty unusual; only a handful of British hoverflies share that feature. The noticeable bend in one of the veins in its wings, visible near the tip of the fly's left wing in the photo above, is also distinctive. The combination of those features, plus the thin black stripe on the fly's face, its dark antennae, the dark lines between the blocks of yellow on its abdomen, and the dark band on its back tibia (the middle section of its leg) covering less than half of the tibia's length help to clinch the ID. This is a male, as determined by broadness of the yellow markings on its abdomen, and the less-pointy shape of the abdomen's tip. One species down, dozens and dozens to go!

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