• Dr Claire Harkin

The season's final outing

The day of my fourth and final Philaenus spumarius collection of the year dawned most inauspiciously, with grey skies and torrential rain. I held my nerve though, and by late morning the sun was out and drying things up nicely, so I headed out to my field site. There were definite signs of autumn approaching, with dried grasses, seed heads and plenty of berries, hips and haws in the hedgerows.

Happily, I still saw plenty of butterflies making the most of the break in the rain, including this still rather fresh-looking Painted Lady, Vanessa cardui.

Painted Lady, Vanessa cardui

As usual with the regular Philaenus collection, my job was to collect between four and eight individuals from five different habitat types within my field site: field margin, hedgerow, woodland ride, mixed scrub and field, and open chalk grassland. The specimens are then sent away to my colleagues in the BRIGIT consortium to have their DNA examined so we can determine things like how far and how fast individuals and populations move and interact. Understanding these factors means we will be better prepared to control the spread of the deadly plant bacterium Xylella fastidiosa if it arrives in the UK.

Collecting a maximum of eight individuals at each site doesn’t sound like much of a challenge, but actually things got off to a rather slow start at Habitat A (the field margin), where it took me well over an hour to find just seven individuals. Not, I hasten to add, because I’m terrible at my job(!) but because we are fast approaching the end of the field season, and numbers are really starting to dwindle. I found plenty of other species to catch my eye though, including the rather splendid Roesel’s bush cricket, Metrioptera roeselii, and nymphs of the green shield bug, Palomena prasina, and the dock bug, Coreus marginatus.

I also rather unexpectedly found a single individual of Philaenus’ larger cousin Aphrophora alni which you may remember from a couple of my previous posts. This was the first time I had seen any Aphrophora species at my regular Philaenus collection site so it came as something of a pleasant surprise.

Aphrophora alni

Another of my aims for collecting is to get a roughly balanced mix of males and females for analysis. Unfortunately, with autumn and the end of the season fast approaching, this becomes very difficult as there are fewer and fewer males left alive. The bulk of mating activity happens a bit before the end of the season, so males tend to die off while females hang around for a bit longer to lay their eggs. True to expectation, I found far more females than males, but was pleased to see a pair of individuals mating in three out of my five collecting pots, so knew I had at least one male from three of my habitats!

Philaenus spumarius mating pair

Luckily, once I moved on to Habitat B, things picked up a bit numbers-wise and I was able to get through all of the remaining collections by about 6pm before it started to get too cold and damp again. By this time my sweep net was absolutely covered in blackberry juice from sweeping in hedgerows and in the woods, a sure sign that it’s time to dismantle my net and get it in the wash, ready for next spring and the start of the new season!

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