I spent an enjoyable afternoon today at BBOWT’s Pavis, Black and Northill Woods nature reserve, where there was plenty of insect activity in the warm, humid conditions. This tree stump was at the edge of a path.
Old tree stumps are always worth investigating for insect life, and this one performed well! There was a small water-filled cavity in the top of the stump.
When I peered into it I saw a small forest of thin whitish ‘stems’. At first I thought they might be fungi, but some of them were moving, and I soon noticed that there were small whitish grubs at the lower end of each stem.
These are in fact one of the ‘rat-tailed maggots’, otherwise known as larvae of hoverflies in subfamily Eristalinae.
They seemed to be busy feeding – all the movement visible in the video clip at the top of this post comes from the hoverfly larvae, some of which are pushing and shoving at the bits of vegetation sunk under the water, all the while keeping their long rat-tails reaching to the surface to breathe air.
The most frequent species in tree holes is the Batman Hoverfly, Myathropa florea, but I can’t be certain that these larvae are of that species or one of its relatives.
Thanks to BBOWT for their work on this peaceful and life-filled reserve.
Today saw the first reasonably heavy snowfall in our part of the Chilterns for quite a while, so we couldn’t resist heading up the hill for some sledging and to visit BBOWT’s Grangelands reserve. The air was crisp, and the snow-enveloped landscape was beautiful. I wasn’t really expecting to find much insect life to watch, so was surprised to see a small caterpillar crawling across the top of some fairly deep snow.
At first I thought this must be a one-off oddity, perhaps dropped onto the snow by a bird or carried there by the wind, but then I started seeing others. I found eight in a short space of time, all seemingly happy to be out and about on the surface of the pristine snow.
On closer examination at least some were caterpillars of the Large Yellow Underwing moth (Noctua pronuba), a well-known and very abundant species in the UK. I hadn’t been aware of its habit of being active in such conditions, but a web search leads to a number of American reports of similar snowy adventures for this species (see this post by Vermont naturalist Mary Holland for example, plus some additional photos on BugGuide). Large Yellow Underwing is an introduced species in America, and can be a pest species. Its winter activities are so well-known there that it also goes under the name of Winter Cutworm or Snow Cutworm.
I’ve always had a sneaking admiration for how well Large Yellow Underwing manages to survive in the modern world, but I’m even more impressed by its hardiness now! Has anyone else seen this snow-walking behaviour in the UK?
[Update at 15 December: thanks to Martin Townsend for pointing out that the brown caterpillar in the photo below looks like it is something other than Large Yellow Underwing, so it’s likely that at least two species were involved.]
Having travelled to Shrewsbury last weekend to speak at the excellent Darwin Festival, organised by Shropshire Wildlife Trust and partners, I took the opportunity to do some extreme entomology. Okay, so The Hollies (next door to The Stiperstones, near Shrewsbury) is a bit higher than where I live, 350 metres as opposed to 100 m, but the altitude can’t be said to be extreme. And although a cold, gloves-on February day might not be the usual choice for bug-hunting – the temperature records claim it was 7-8 °C, but with a biting wind it felt a good deal colder – that wasn’t really extreme either, although it did make it hard to keep the beating tray steady. No, the extreme thing here was the trees I was searching for signs of insect life: a range of ancient Holly trees, some believed to be about 400 years old.
The Holly trees at The Hollies are an extraordinary range of shapes. Many are individual isolated trees that have been sculpted by wind and time into gnarled shapes that stretch and lean. There is precious little shelter to be had, either for the trees themselves, or any insects that might live in or on them, or indeed for the visiting entomologist. This must be one of the few Holly populations anywhere in Britain where the Holly Leaf-miner fly (Phytomyza ilicis) struggles to gain a foothold – I found just a few mines on one of the slightly less exposed trees.
But a lot of insects clearly do make their home here, as testified by the peppering of beetle exit holes in the trunks and limbs of the trees. And in fact the first insect to fall out of a Holly and onto my beating tray was the Lesser Thorn-tipped Longhorn Beetle (Pogonocherus hispidus). Larvae of this small (5mm) but attractive beetle develop in the small branches of a range of trees including Holly. Do have a look at thesetwo great close-ups by John Hallmén on Flickr.
An hour or so of beating and grubbing around the trunks of the the trees produced a small list of other species:
Holly Speckle fungus, Trochila ilicina (a tiny fungus that only grows on dead Holly leaves)
A modest list, but not bad for a very cold February afternoon, especially as all but two (Porcellio scaber and Anthocoris nemorum) of these invertebrates are new records for the Stiperstones area, according to the useful list compiled by Pete Boardman in 2010. I find it comforting that these many of these species have probably been happily living at The Hollies for many generations, over the centuries since the current hollies started growing.
The Hollies is a Shropshire Wildlife Trust reserve and SSSI, so thankfully its special character has been recognised and is being looked after. It’s a shame that so many of the hollies have had to be fenced off, making it look rather like a tree zoo – presumably this is to prevent the trees being damaged by grazing stock. But the ancient hollies still work their magic, redolent of centuries of human interaction with the landscape. There’s more about the history of The Hollies on Sara Bellis’s blog, where she comments that in the past small boys would have been sent up the trees to collect the higher, less prickly leaves, as livestock feed. Since I was accompanied on my visit by a small boy in the shape of Kitenet jnr it’s a shame I didn’t think to put him to gainful employment for once …
Last week I had the pleasure of teaching my first course for the fantastic Field Studies Council, at their Epping Forest centre. The day seemed to go well, and for me it was great to be out talking about wildlife-watching among the venerable old trees of the Forest.
I’ve added some of the materials from the course to a new biological recording section of my website, including information on recording, tips for photography and using keys, suggested surveys to try out, links to further resources and some field exercise sheets (downloadable). As ever, feedback welcome to improve what’s there and fill in any gaps I’ve missed.
While reading up for the course I went back to the late Oliver Gilbert‘s very enjoyable book The Lichen Hunters. Despite not being any sort of lichenologist myself I loved reading about the exploits of Dr Gilbert and his colleagues in tracking down unusual lichens in a range of habitats, from pristine rocks high in the Cairngorms to the ‘ancient tarmac’ of abandoned WWII airfields. Finding lichens in mountainous habitats requires impressive feats of physical endurance – anyone want to start a campaign for lichen-hunting as an olympic sport?
The book contains one of my favourite biological recording quotes, capturing some of the emotions that come from close contact with wildlife and wild places:
“You go to look for lichens and find in addition familiarity, beauty, companionship, laughter and the warmth of friends.”