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.
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.
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.
Last Sunday morning I was walking in the Buckinghamshire Chilterns. I was feeling a bit tired and unenthusiastic, and for once was not really thinking about recording insects. But it’s impossible to completely turn off the entomological instincts, and a fairly large cuckoo bee (or nomad bee, genus Nomada) caught my eye. It was flying among the vegetation at the top of a bank on BBOWT‘s Grangelands nature reserve.
I took a quick snap but wasn’t very careful about it, and the bee soon vanished into the undergrowth. But it had looked somehow different, and as I walked home it dawned on me that it just might have been something special. By the time I got home I was keen to see the photo, but I’d done a really poor job – blurry and distant. Even so, what few details I could make out were consistent with it being something potentially very special: was there a chance it could be the Armed Nomad Bee, Nomada armata.
That, however, is a Red Data Book 1 species, and listed as being of ‘Principal Importance’ in the NERC Act. And as far as I knew it hadn’t been seen anywhere outside Salisbury Plain for about 50 years. So a grotty blurred photo wasn’t really going to cut it.
Nomada bees are ‘cleptoparasitic’ bees that take over the nests of other bees. The host for the Armed Nomad is Andrena hattorfiana, the Large Scabious Mining Bee, itself a rare species but one that has been spreading, and was first found in Buckinghamshire in 2007, by Aaron Woods, near Beaconsfield. Following that it has been seen at a few other sites, including at Grangelands, where Ryan Clark discovered it a few years ago. So it was at least conceivable that the Armed Nomad had started to follow the expanding range of its host.
But I needed better supporting evidence! And it was getting late in the afternoon by now. So back up the hill I went. Needless to say there was no sign of the female Nomada in the original location, so I set off in search of Field Scabious flowers, which are the flower required by Andrena hattorfiana, and also visited by Nomada armata. After about an hour and a half of searching, and on the opposite side of the reserve from the morning’s sighting, I saw a bee on a Field Scabious flowers.
Nervous with excitement I nearly fumbled the net, but managed to catch what turned out to be a male Armed Nomad. Some slightly better photos ensued, and as soon as I got home I sent these to Stuart Roberts of BWARS, who very promptly confirmed the identification – thanks Stuart.
As far as I know this is the first time the Armed Nomad has been seen in Buckinghamshire, and the first time for about 50 years that it had been recorded away from Salisbury Plain – or so I thought …
I reported the find to BBOWT, who passed the message on to Peter Creed, author of A guide to finding bees in Berkshire, Buckinghamshire and Oxfordshire. To my amazement Peter got in touch to say that he had also found Nomada armata the same weekend as I did, but at another BBOWT reserve, Dry Sandford Pit in Oxfordshire (vice-county Berkshire). This is a site where it had been recorded before, back in the 1970s. The known range of Nomada armata had suddenly expanded considerably!
Another trip to Grangelands a couple of days later produced good sightings of the host bee Andrena hattorfiana, and one further male Nomada armata. So it looks like it has established itself on the reserve.
It’s always encouraging to see rare species making a recovery, and while it is early days for this one the hope is that both host bee and cuckoo will continue to strengthen their populations and distribution. And BBOWT’s reserves are clearly playing an important role in allowing them to do so. It’s intriguing to think what journeys the Nomada must have made to get from Salisbury Plain to the Buckinghamshire Chilterns.
Just outside my front door there is an untidy patch of Green Alkanet. It’s not the ideal place for this rather scratchy plant to grow, but I cannot bring myself to dig it out, because it’s a favourite spot for some black and yellow caterpillars to feed. As a result, every summer there’s a day when I open the front door and get treated to the breathtaking sight of a newly emerged Scarlet Tiger moth – just fabulous.
Each year the first of these glorious moths surprises and amazes me, even though it’s been a regular experience since Scarlet Tigers colonised our vilage in 2009. It’s still a mystery to me how they first arrived: as far as I know there were no nearby colonies. Whatever the source, they are very welcome.
And this freshly hatched pair had wasted no time in getting to know each other – hopefully that bodes well for another Scarlet experience next summer – definitely one of life’s joys.
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.]
What happens? Lots of things! We’ll be opening a moth trap, sorting moths into their correct families, studying the niceties of species identification, exploring woodland, meadows and hedgerows for moths by day and by night, joining in with quizzes and exercises, and much more. If you’ve ever wanted to find out more about how moths live, what role they play in habitats and food chains, and how to observe them for yourself, this is your chance.
This course runs on Saturday 14 May 2016 at Bushy Park in west London. It starts at 2pm with classroom and field sessions, and then in the evening we’ll head out with moth traps to put our skills into practice. Click here for full details and to book a place.
The course is based in a part of Bushy Park that is not normally open to the public, and allows access to flower-rich meadows, woodlands and wetlands. We’ll use a mix of classroom presentations, activities and fieldwork to help you get to know more about moths and what makes them special. You don’t need to know anything about moths already, beginners are welcome, and if you’ve already started taking an interest in moths the course will help you develop your knowledge further. Contact FSC to book your place, and come prepared to be amazed by moths.
Maybe it’s the time of year: during the next few weeks Buckinghamshire is bursting with meetings, conferences and general sociability for anyone interested in recording and conserving wildlife in the county.
First up is the spring indoor meeting for the Buckinghamshire Invertebrate Group, on Saturday 14 March, 10am to 1pm, at Wendover. Anyone with an interest in insects and other invertebrates in Bucks is welcome to join the (free) mailing list for the group, which produces an excellent annual Bulletin and organises a range of field and indoor meetings. This year is BIG’s 25th anniversary, which will be celebrated at the Recorders’ Seminar (see below). Our indoor meeting is a chance to catch up with friends, help plan the year’s field meetings and hear all the latest bug-related news. To join and get the meeting details contact BIG.
On Saturday 28th March there is another insect-focused day: the Conservation Review Day organised by Upper Thames Branch (UTB) of Butterfly Conservation. This is being held in Berkshire, at Dinton Pastures near Reading, but UTB covers Bucks as well as Berks and Oxon, and the day’s events include talks by Martin Albertini and Tony Gillie on Striped Lychnis moth in Bucks, and by Ched George on Duke of Burgundy butterfly in the Chilterns, as well as more general presentations that will be of interest to anyone involved with the conservation of butterflies and moths in the region. Please come prepared to join in the discussions.
Every year BMERC (the local environmental records centre for Buckinghamshire and Milton Keynes) organises a splendid Wildlife Recorders’ Seminar, held as Green Park near Aston Clinton. This year’s programme (Word document download, includes booking form) is in part a celebration of the 25th anniversary of BIG, but also has John Sawyer outlining new developments for the National Biodiversity Network, as well as presentations on freshwater life and water quality from the Environment Agency, and on using DNA for environmental monitoring. BIG then takes centre stage with a series of short presentations from members of the group, and the day concludes with Buglife‘s Sarah Henshall focusing on the invertebrate paradise that brownfield sites can provide. Thoroughly recommended – I should warn you that I’m also down to speak, twice, but both of these are for short periods 🙂
Finally, on Thursday 23 April (and once again at Green Park) there is a fascinating conference with the intriguing title of “Local Spaces : Open Minds” (click for details and booking form). Organised by the Chiltern Commons Project, this day explores what role the Chiltern Commons could play in the environment of the future – how can they best play a part in conserving species, providing outdoor space for healthy living, and contributing to landscape and heritage? You may not realise it, but there are around 200 commons in the Chilterns, many of which have considerable biodiversity and historical interest, as well as playing a role in the wider landscape-scale conservation issues relevant to us all.
Sadly I can’t be at all these events but each looks like it will be worthwhile and enjoyable – join in if you can.
Last Sunday I attended the excellent annual conference of the Garden Moth Scheme, which was well-attended, informative and enjoyable. And most importantly it showed how valuable it can be to record in a slightly more standardised way that we might otherwise do. Read on for more on the benefits of structured recording, and how you can join in with GMS.
Lots of people record moths and send their records in to their county moth recorder, which is an excellent way of finding out which species are where and contributing to the National Moth Recording Scheme. However, using this data for monitoring purposes is not straightforward, as there are so many variations in how, where and when people record their moths. To get good data on population trends for moths a more structured approach is needed.
The largest-scale example of structured moth recording is the Rothamsted Insect Survey (RIS), which celebrated its 50th anniversary in 2014. One of the RIS projects gathers data from Rothamsted moth traps positioned around Britain and Ireland. The first of these traps was used in the 1930s and 1940s, and following a gap in the 1950s an extensive network has been developed since the 1960s. This has provided an unparalleled set of long-term monitoring data for moths, and unfortunately what the data tell us is not very good news: the one trap that was running before the second world war was producing a lot more moths than traps have done subsequently, suggesting that there was a major decline in moth abundance in the 1950s (see graph on right). And the declines have continued: Rothamsted data was used in a joint project with Butterfly Conservation to assess the State of Britain’s moths over the last 40 years, from which the headline news was that two-thirds of widespread moths have undergone a significant decline, especially in southern Britain.
The Rothamsted moth traps are run by a network of volunteers, and new volunteers are welcome, but it is quite a big commitment. You have to have space to install the trap, and you have to commit to running it every night of the year for at least five years. Many of the Rothamsted traps are situated in places such as Field Studies Centres or research institutes.
But there is another moth monitoring scheme that you can join in with much more easily. The Garden Moth Scheme asks its participants to run a moth trap once a week (on the same night each week if at all possible) and to record the numbers of a suite of common species (you can of course record all the species you see if you wish, but the GMS focuses on a main list of around 220 species). Even if the weather is unpromising it’s still important to run your trap, and if you have a night where you record no moths that is still useful data! It is this regular pattern of recording once a week whatever the weather that helps give this survey its structured data, and allows for robust analysis of the results.
All in all the GMS is an excellent way for moth recorders to add an element of structured monitoring to their recording, without doing anything other than running a moth-trap in the garden, the sort of thing that moth-recorders love to do anyway! If you want to join in for the 2015 you need to be quick – recording is due to start this coming Friday 6 March (although at a push you can start a week or two later if you miss that first deadline), so head straight over to the GMS Getting involved page. I’m going to give it a go this year, and I look forward to seeing how my results fit in with everyone else’s.
If you do take part in GMS, please remember to copy your results (along with all your non-GMS moth records) to your county moth recorder as well.
New research suggests that light pollution can reduce mating success in Winter Moths
Moths are in trouble – evidence is accumulating (see Butterfly Conservation and Conrad et al. 2006) to show that many moth species are in decline, especially in the southern half of Britain. But what are the causes? Research is showing that a combination of factors is likely to be involved (Fox et al. 2014), with habitat change or loss and climate change likely to be a large part of the story. But another factor that could be impacting on moths is ‘light pollution’, the tendency for humans to want their own habitat to be lit up at night, so we can work, play and feel safe walking the streets. The night-time glow of towns and cities is visible from miles away, and even in rural areas roads, shops and houses may be illuminated.
Could all this light be affecting the lives of nocturnal creatures such as moths? It seems plausible, but it’s hard to prove, not least because the way most of us go out and look for moths is by putting bright lights out to attract them. How to find out what light pollution does to moths when they’re hard to observe in the dark?
A newly published paper (“Artificial light at night inhibits mating in a Geometrid moth” Van Geffen et al. 2015) has used an ingeniously simple method to investigate this, and the results suggest that we should indeed be worried about what light is doing to moths. Koert van Geffen and colleagues carried out their study in the Netherlands, and chose Winter Moth as their subject. Why Winter Moth? One reason why they make good study subjects is that their habits are a bit more predictable than for many moths: female Winter Moths are flightless, and one they emerge from their cocoons under ground they ascend the nearest oak tree and wait for the males to find them. And there is an established method for trapping them, by setting up ‘funnel traps’ that steer the females into a container once they climb far enough up the oak tree.
So Winter Moths are going to be climbing their oak trees, and if you shine a light on the tree the females can’t fly away. The Dutch team set up a series of different lighting regimes directed at oak trees, using green, white and red light, plus unlit trees for comparison. They counted the females on each tree, and checked them to see if they had mated. The results seem to me to be quite dramatic.
By far the greatest number of female moths were caught from the unlit trees. Of the illuminated trees, white had fewer than red, and green fewest of all. All lit trees had more moths on the shaded side than the lit side, but only under red light did even the shaded side produce anywhere near as many moths as the unlit trees. And there was a big difference in mating success: 53% of females caught from the unlit trees had mated, but only 28% of the females under red illumination, 16% under white, and 13% under green.
Van Geffen et al. also studied male moths using pheromone traps positioned under different lights. The differences here were less dramatic but still apparent, with fewest males caught under red light, more under white, more again under green, and the greatest number from unlit traps.
This is of course just one study of one moth species, but it showed that in this instance artificial light reduces the activity of female moths, and also reduces the male response to female pheromones, resulting in decreased mating success. The lights used in the experiment were LEDs with a light intensity of 10 lux – street lighting can be much brighter than this, up to 60 lux (Gaston et al. 2012).
Relatively simple and effective research, providing more evidence of the pressures on moth populations. Can we do anything to reduce the effects of light pollution? Gaston et al. 2012 review possible ways of preventing too much light escaping into the wider environment. Further useful information and advice is available from Buglife’s research and Campaign to Protect Rural England’s “Dark Skies” pages. For instance, we can reduce the intensity of artificial lighting, direct it more precisely so there is less overspill, and leave lights on for shorter periods so that they are only illuminated when they are actually needed. This not only has the potential to help wildlife, but to reduce energy use and costs as well – moving lighting in this direction has got to be a no-brainer.
By taking action at home and encouraging local authorities and businesses to do likewise we can all help shed some darkness and take moths out of the spotlight.
With mobile devices (smart phones, tablets, pads and pods) becoming increasingly widespread, more and more people are accessing digital resources via apps and mobile-optimised websites. To explore this trend in the natural history context, the Communicate conference ran a session entitled “Apps for Engagement” (Wednesday 24 October 2012), at which I gave a brief presentation on iSpot’s approach to engaging with its mobile audience. Here are some links relating to that presentation.