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Holtspur Bottom’s boring beetles

Photo: BC volunteers at work clearing scrub (photo by Nick Bowles - kitenet jnr is wielding a bow-saw at the bottom-right of the picture!)
Upper Thames Branch volunteers at work clearing scrub (photo by Nick Bowles – kitenet jnr is wielding a bow-saw at the bottom-right of the picture!)

In winter 2017-18 some young Ash trees were felled at Holtspur Bottom Butterfly Conservation reserve, to open up and restore an area to chalk grassland. Logs from this felling were stacked. Last weekend we returned to clear another area, and had to move some of the logs from the previous winter.

Photo: galleries sculpted by the Ash Bark Beetle
Galleries sculpted by the Ash Bark Beetle

In the intervening year rather a lot of beautiful patterns had been sculpted onto the logs, the handiwork of the Ash Bark Beetle Hylesinus varius. The females excavate an initial ‘vestibule’ in the bark, in which they mate with the males, and then bore two long egg galleries in opposite directions from the vestibule, under the bark, laying eggs at intervals along them. On hatching, the larvae start to bore another set of galleries at 90° to the egg gallery, gradually expanding the gallery width as the larvae grow. They pupate in a cell at the end of the larval gallery, from which the next generation of adult beetles emerges and bores an exit hole through the bark to fly off and find a suitable Ash log for the next generation.

Photo: the various galleries constructed by the beetle
The various galleries constructed by the beetle

The Ash Bark Beetle only enters the bark once the tree is already dead or dying, and is not believed to spread fungal diseases, so to me this is a harmless and fascinating aspect of biodiversity. As with many insects, the beetles are quickly followed by a range of parasitic wasps, and a study in the Czech Republic found that over half of the Ash Bark Beetle population in their study area succumbed to the parasitoids (Nakládal and Turčáni 2007). So there is a whole chain of life going on under the bark of the dead wood! It’s good to know that a by-product of the conservation work we carry out to benefit the grassland plants and butterflies provides habitat for these tiny but fascinating creatures.

Photo: Ash Bark Beetle adult (photo by WWalas via Wikimedia Commons)
Ash Bark Beetle adult
(photo by WWalas via Wikimedia Commons)
Photo: multiple galleries in one log
Multiple galleries in one log

For more information on bark beetles see:

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Extreme entomology at The Hollies

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.

Pogonocherus hispidus on Holly bark at The Hollies

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 these two 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:

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 …
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Identifying invertebrates: downloadable keys

The previous post listed some identification keys that run online, as more-or-less interactive websites. This post includes some sites that have keys you can download (usually as pdf documents) and print out. See also my bookmarks on delicious.

Various groups
Some excellent materials, many produced by Brian Eversham, are available on the website for The Wildlife Trust for Bedfordshire, Cambridgeshire, Northamptonshire and Peterborough [link updated at October 2012]. These include keys to insect orders, grasshoppers and bush-crickets, water bugs, ants, beetle families, longhorn beetles and soldier beetles (plus other non-insect groups). NB that most of these are tailored to the Bedfordshire area, and do not necessarily include all UK species (the exception being the soldier-beetle one by Dr Mike Fitton, which does have all species).

Lepidoptera
Various resources, including an identification guide to grass moths (Pyralidae: Crambinae) compiled by Nick Asher, can be downloaded from the Berkshire Moth Group.

Hymenoptera
Some keys to selected groups of bees and ants are available from BWARS.

Diptera
Dipterists Forum has produced some really good downloadable keyes, some of which are available only to DF members; these include a very well-illustrated key to Diptera families, a key to Scathophagidae (dung-flies and allies), both of these by Stuart Ball, and a version of Alan Stubbs key to hoverfly tribes illustrated with photos by Stuart Ball – Dipterists Forum is worth joining just for these, let alone all the other benefits!

Available to anyone is the set of draft keys to craneflies, by Alan Stubbs, and keys to stilt and stalk flies, by Darwyn Sumner.

Coleoptera
The recently established Beetle News has included keys to various small groups of beetles in its first few editions, and they can be downloaded from the Amateur Entomologists’ Society.

Field Studies Council
This listing from the FSC includes many of their published keys, available to purchase, but also some older papers that are free to download, including Unwin’s key to Diptera families, and the now slightly out-of-date key to slugs by Cameron, Eversham and Jackson.

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Identifying invertebrates: online keys

On Saturday 30 January, Roger Hawkins and I are running a workshop for the BENHS on using keys for insect identification. We’ll mostly be working with published hard-copy keys, but we’ll include some online keys as well. Below are some examples for various invertebrate groups.

I must admit that I don’t yet make much use of online keys. This is partly because I’m fortunate in having a good range of printed keys available to me, and I’m sure it’s also partly a case of ‘sticking with what I know’ rather than spending time learning the online ones (all keys require time spent on them to get familiar with their particular approach). However, I think there are still some problems with online keys, from the practical one of having to have a computer within easy view of your specimen or microscope, to more intrinsic issues about the ease of flicking through a book to compare different sections, as opposed to having to switch between different windows on a computer.

However, online keys are likely to become more widespread and will no doubt get better as time goes on, just as printed ones have (and continue to do so), and no doubt the two will be seen as complementary rather than an either/or choice.

See below for some online keys to try out. For a longer list (including plants and other groups as well as invertebrates) see my bookmarks on delicious, and let me know if there are any other good keys out there, or any thoughts you have on using online keys. A post on downloadable keys will follow.

Various groups
The most comprehensive set of online keys that I am aware of is the DELTA Intkey system. This requires you to download some software onto your computer, after which you can either download various individual keys, or run them from the web.

At the moment there is quite a wide range of keys available within this system, for various taxonomic groups (not just invertebrates) and different parts of the world, but for UK insect purposes they include:

Orders of insects, families of Coleoptera, families of Diptera, genera of Ephemeroptera, families of Hemiptera, families of Hymenoptera, families of Lepidoptera, genera of butterflies, genera of Geometridae, genera of Noctuidae, species of Phyllonorycter, species of Odonata, genera of Orthoptera, families of Trichoptera.

These are multi-access keys so that you can answer the set of questions in any sequence, and need only answer the ones you’re confident of – the system will endeavour to give you a best match of one or more names for your specimen. I’ve made most use of the family keys for Coleoptera and Diptera, but I have to admit they’ve not proved as helpful as I hoped, and I still tend to return to paper-based single-access (dichotomous) keys for backup. But it is always good to have additional keys available for comparison, and no doubt if I used them more I’d get more used to their idiosyncrasies and perhaps find them more helpful.

There are some draft online keys available on iSpot (part of OPAL), including a simple ‘key to minibeasts’ – this part of iSpot is still under development, and there’ll be more to come.

Coleoptera
The Watford Coleoptera Group (click on “ID aids”) are making a range of identification aids available, some in the form of keys, some as notes on particular species or groups of species.

Hymenoptera
[added on 10 February 2010]
The Natural History Museum provides a very useful key to bumblebees.

Diptera
These online keys to various families of Diptera are managed by Paul Beuk, who also runs the excellent Diptera.info. You may need to register on Diptera.info to get full access to the keys. Some of these keys are online versions of existing printed keys, others are new (e.g. includes the best key I’m aware of for genus Sylvicola in family Anisopodidae).

Not a key, but some very helpful support for keys is provided by the Anatomical Atlas of Flies, from CSIRO in Australia. This is a truly excellent web implementation of a morphology diagram and glossary of names for parts of flies, using detailed close-ups of real insect specimens. But it needs a good broadband connection to work at any speed!

Mark van Veen’s Faunist is a Dutch site with keys to various families of Diptera, plus Odonata, Orthoptera and sea-shells. The latter three are in Dutch only, but most of the Diptera keys are in English. They are well-illustrated and easy to use, and I think cover most of the British species in the families included. Plenty of information about the species is given (but remember that this refers to the fauna in Holland, which will include additional species and different habitats/behaviours compared to the UK).

Some of these keys to robber-flies (Asilidae) by Fritz Geller-Grimm are applicable to the UK (others cover various parts of the world).

For those flies with larvae that produce leaf-mines (largely Agromyzidae, plus a few Anthomyiidae etc.) there are keys based on the foodplant on the excellent UK Fly Mines site.

Lepidoptera
Similarly, for leaf-mines of Lepidoptera try Barry Dickerson’s online key, on the British Leafminers website. This is largely based on volumes 1 and 2 of “The Moths and Butterflies of Great Britain and Ireland”, but with some additions and revisions. A very useful resource (but be aware of all the non-lepidopterous insects that also make leaf-mines, most of which are listed, but not keyed, elsewhere on the site).

Butterfly Conservation/Moths Count provide a simple key to day-flying moths.

Odonata
There is a good identification key to Irish dragonflies and damselflies, but it covers males only, and not all UK species are included.

Mollusca
The Conchological Society provide some online keys and other identification notes for various groups of snails and slugs.

Arachnida
This German website has a key to European spider families.

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invertebrate recording schemes – call for atlas records

Three national recording schemes are currently collating records for their forthcoming national atlases, and have deadlines fast approaching. I managed to get myself sufficiently organised today to send off my records, so am feeling smug, and if anyone else has data to contribute I’m sure it would be very welcome.

  • Ladybird recording scheme: atlas due for publication in 2010, records accepted up until “spring 2009” (Coleoptera: Coccinellidae) – if you can recognise a Seven-spot Ladybird you can contribute to this!
  • The Larger Brachycera recording scheme covers several families of Diptera (flies), including soldier-flies, horse-flies, bees-flies and a few others. Records needed “as soon as possible”.
  • The Centipede (Chilopoda) recording scheme also has an atlas in the pipeline – not sure of the timescale, but again all records are requested. Centipedes are not the easiest creatures to identify, but there is a very good recent Field Studies Council key to them, by recording scheme organiser Tony Barber.
Geophilus carpophagus