Back in January I dug a few pitfall traps in my garden. These are simply plastic cups set flush with the ground and covered with a lid to keep rain out. The lid also serves to block larger animals – vertebrates like mice or frogs – for what I’m interested in catching here is ground-dwelling invertebrates. The traps can be filled with preserving fluid, but in my garden I’ve kept them dry so I can retain any specimens I particularly want to look at whilst letting anything else go.

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A cunningly concealed pitfall

Beetles are the most common target of a pitfall trap. So far, all three traps have added species of beetle to my garden inventory. On the one occasion the trap set in the middle of the lawn* flooded, an individual of the mostly subterranean ground beetle Clivina fossor was floating in the top. It’s a curious looking mole-legged creature that twists around what almost looks like a ball-and-socket joint between abdomen and thorax, all the better to contort through small gaps in the soil.

My latest trap round turned up no beetles whatsoever, but when I tipped out the contents of the raspberry bed trap I immediately noticed something pinging about like a rubber ball, much too large to be one of the usual springtails. Flattened from side to side and with a variety of legs and other appendages sticking off seemingly at all angles, this was an amphipod crustacean. Wait: a shrimp, in the garden?!

It turns out there is one species of terrestrial amphipod in Britain, Arcitalitrus dorrieni. It’s an introduction from the forests of New South Wales that was first found in this country back in 1924 on the Isles of Scilly. Common names include landhopper, woodhopper and (my favourite) lawn shrimp. They’ve been well established in the south and west for some years now, mostly on the coast, but seem to be spreading. I first discovered the existence of this creature when I found them under flowerpots in our garden in Twyford, just to the east of Reading. They’re established in the London area, and have clearly made their way along the Thames valley as far as Newbury. Of course this latest leap may have been made in one go by hiding out in a plant pot in our removal van! Perhaps that’s a clue to how this species gets moved around.

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By ‘Sarah’ on Flickr CC BY-SA 2.0

The British Myriapod and Isopod group are collating records of this species and also published an informative paper last year updating the landhopper’s U.K. distribution and providing information on how to separate it from other (less common) introduced terrestrial amphipods. Dave Hubble also provides more detail on his blog. I presume it is fairly under-recorded, so why not go pick up some pots in the garden and search for this rather entertaining skipping shrimp?

*Or what I will hopefully be calling the meadow later in the year.

Coffee update (see previous entry):

Somebody at Waitrose customer service replied to say they’ve passed on my enquiry to a colleague for a full response. Nothing for a week or so. In the meantime we’ve discovered that Riverford, from whom we order a weekly vegetable box as well as milk and other bits and bobs, have just started selling a shade-grown Fairtrade coffee produced by Equal Exchange. We’ll order a bag and give it a go! 

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