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Saturday, August 8, 2020

We've had three hot nights in succession

Well there's been more than three of them recently but last night (Friday 7th) looked like it was going to be a proper warm 'un. It was forecast to stay above 20 degrees all night meaning that with a bit of luck there would be good dispersal of inverts and hopefully some good beetles. The main question was where to go?

A quick check in with fellow moth-er Bill and we decided to head back out to Chippenham Fen for our 3rd trip of the year. But before I left I decided to set up a MV and an actinic trap at home to see what else might turn up.

We got three traps out at dusk and one of them was soon absolutely hooching with flying ants. Given that the other two were relatively ant-free I suspect we just happened to site it near the exit holes of a colony, but then again considering how wet the ground still was, maybe not.

We soon had several Geotrupes spiniger bombing the white sheet and the numbers of beetles gradually built up. Moths started arriving too after an hour or so and we recorded about 120 species before we packed up just before 2am.

Beetle wise there was a fair amount of small fry that I will need to dedicate a few hours too at some point but there were a few new species that were instantly recognisable.

First up was a new species of tenebrioid, the relatively common Prionychus ater. Another one of those species that I just hadn't bumped into yet. There are still a dizzying number of those!

Just as we were packing up I noticed an Opilo mollis sat on the tripod holding the MV bulb. I'd heard of their tendency to drop and disappear before getting anywhere near them so was pleased to get hold of it. However, I had no spare pots so decided to pop it in one with a Leiopus nebulosa agg. For future reference, Don't! The Opilo soon removed the longhorns legs and antennae and the poor thing was alive but a quadriplegic 😞

Not good in company!

I managed to get home at about 2.30 and then spent the next 30 minutes looking at what had turned up at the garden traps. It wasn't as busy as I'd hoped but before hitting the sack for a couple of hours I did find a single White-spotted Pinion which was a new addition for the garden list.

Waking up at 5.30 a little worse for wear I spent the next hour or so going through the traps. The most obvious thing was the sheer number of Bradycellus verbasci. There were literally thousands. 10s or hundreds on every egg box and the bottom of the Robinson trap was an ever moving mass of bodies. This made seeing and picking out the small stuff (and even some of the bigger stuff) quite difficult.

Then things began to get good. On the second egg box I turned was the beetle that I've been dreaming of catching on a warm summers evening for some time. The beautiful and rather flat Polistichus connexus.

This is a species that lives in cracks and fissures in the ground, mainly around the coast in the extreme south-east of England. It has been turning up at light traps around the Thames basin on very warm nights but I wasn't sure if it could/would make it as far as Cambridge. Lucky for me it did (plus it brought a friend) and I also know that at least two other Cambs moth-ers recorded it last night too.

There was lots of the other usual stuff: carabids, staphs etc. I potted a few of the smaller Ophonus species as well for dissection. These were in amongst the huge numbers of Bradycellus, and large numbers of Harpalus rufipes and Ophonus ardosiacus.

As I began to fade this afternoon I decided to take a quick look at these under the microscope. The first one I looked at made me scratch my head.

Why did I pot a Harpalus rufipes? Taking my eye off the scope I could see why, this beetle was small. 10.5mm. H. rufipes  are generally much bigger. I remembered that there was a closely related species that is very rare in the UK. but that had been recorded coming to light.

Harpalus griseus aka the Brazilian (to find out why that name then read the end of this post by Mark Telfer). The pronotal shape looked ok for griseus so I posted a pic on the Facebook group. Mark replied that it looked good but would need to see the sternite pubescence.

So there's hair in the middle but the sides are smooth

A slightly different angle to give a clearer shot.

So, my initial hunch turned out to be right. Looks like this is H. griseus. Probably new for Cambs too and another example of the amazing ability of beetles to disperse on warm summer evenings. Beating and sweeping may be in the doldrums at the moment but light trapping is really delivering the goods.

[EDIT: the last UK record was in Norfolk in 2012 according to the Carabid Recording Scheme]

Today's blog title takes me back to being an angry young man growing up in Yorkshire. I'm now just an angry middle-aged man living in Cambridge.


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