Significant subtle shifts since the last post. Shorter days, a return to rain at some time on most days and lots of seasonal observations – some familiar and, as always, some completely novel for this blogger. (last year almost no observed insect visits to Linaria genistifolia. This year masses of bumblebees on its yellow flowers. Why?)
The garden has also briefly moved to a hiatus with perhaps fewer flowers than at any time since February. This is probably the result of poor planning on our part, partly because some plants have still not caught up after the very cold spring, but perhaps mainly because many of our stalwarts have flowered for a shorter period than normal. In turn this shorter flowering time hasn’t just been as a result of the long hot dry July, but more, I think, because of the abundance of pollinating insects around in the garden during all this clement weather. (last year barely enough saved sweet pea seeds to fill one tyre with plants this spring. This year masses of filled pods). (This year saving broad beans from a mix of Stereo (small bean size) and Witkiem Manita (large bean size), grown together over the last couple of years, has resulted in a converging bean size, and at least half the pods with 6 beans per pod). (Aconitum ‘Spark’s Variety’ still flowers on, with masses of bumblebee visits, since the flowers seem to be sterile and so no seed is set to bring flowering to an end).
This is a point which I discuss in my ‘Planting For Pollinators’ film/talk, which we took to the rather grand setting of the Shrewsbury Flower Show last week. This presented new challenges, in part because we couldn’t take along our own familiar equipment. Fortunately I have a phobia of arriving and having to talk without the prop of my film and sound footage, so had taken 4 different and possible ways of displaying them. This was just as well, since the promised first options on site didn’t turn out to be workable, in what was an enormous marquee, with very small screens. Still, poor quality images from a DVD were better than none at all, and many thanks to Brian Harper, Jordan and Gareth for help with troubleshooting the technical problems. It also meant having to use a hand held microphone for the first time, which as Fiona told me afterwards was in fact an advantage since it at least prevented me from waving ONE hand around as I became enthusiastic at particular points. It also allowed me to rise in volume to the occasion, as one of the brass bands marched past the tent at the same time on each of the 2 morning sessions. The Shrewsbury Flower Show is staged in a wonderful setting in the heart of this gorgeous Shropshire town in a loop of the River Severn, and we felt very privileged to have been asked to attend, particularly since we were booked to follow on from Chris Beardshaw,who has always impressed us with his intelligent and articulate design, advice, media and charity work in the gardening field. Click here for Chris Beardshaw’s website. He’s also remarkable in achieving all this in spite of his personal battle with crippling arthritis from the age of 13, which led him to create his gold medal winning garden design for Arthritis Research UK at this year’s Chelsea Flower Show. Images of the garden’s design are also featured on Chris’ website.We had plenty of time left to wander round the show, before heading back to Wales for family and friend events and the vital weaning of our lambs, which in the end produced just a single day of noise from one of the ewes and its separated offspring. No empty nest syndrome afflicting these ovine mothers, just relief at escaping udder pummelling from the now chunky lambs. But a different sort of empty nest syndrome played out and intrigued me around the same time. We were expecting some garden visitors and I’d done a quick weed of the cobbled area around some of the plants we have for sale when I spotted a couple of very large wasps on the yard. But what was going on?
Was one attacking the other, or were they mating? I’d just seen a video capture of what seemed to be mating bumblebees, shown me by a garden visiting friend, and this looked pretty similar. Whatever was happening, it was taking place in pretty slow motion, so I nipped in for the camera. Needless to say, they’d moved on when I returned, but scouting around I then found a whole group of similar sluggish but mainly very large wasps. There’s a really good identification guide to the common species of social wasps, created by Trevor and Dilys Pendleton in Nottinghamshire, which you can access by clicking here. From this I gleaned that these wasps were probably the tree wasp species, Dolichovespula sylvestris, although they seemed to lack the tiny central black mark in the middle of the face. Looking around a bit more I spotted that most of them had ‘fallen’ out of a hole under the eaves of the cowshed above.Some were still moving in and out of what was obviously the entrance to the nest. But why were they so sluggish? They almost looked drunk. And why the size difference?It turns out that tree wasp has quite a short life cycle, with the overwintered and mated queen building a nest from scratch in spring using chewed up wood fibres mixed with saliva (wasps lack the glands allowing wax manufacture that honeybees possess). Over the years I’ve collected a few smaller wasp nests, and after reflecting that their makers qualify as ‘master craftsmen’ bought a vintage glass display dome to protect their fragile paper-thin twin-walled ‘mouthiwork’ constructs. The queen starts laying fertilised eggs, using sperm from a store resulting from mating events the previous autumn. Any fertilised eggs will result in diploid females (2 sets of chromosomes), which form the worker wasps of the new colony. The queen catches insects and chews them up for the larvae to feed on. In turn the larvae secrete a sugary solution which the queen, and subsequently female workers feed on, as well as visiting early spring flowers (like gooseberries) for nectar.
So wasps have a dual beneficial role in gardens and landscapes as potential early season pollinators and also predators of smaller nuisance and plant damaging insects. But what was going on with these large and sluggish wasps? As the queen runs out of stored semen in early August, the eggs laid lack the second chromosome, and so being haploid develop into smaller male wasps and also new queen wasps. And eventually the queen stops laying altogether.
At this point, partly because there are now no secretion producing larvae for the adult wasps to get nutrition from, the colony structure breaks down and wasps will leave the nest. Perhaps their sluggishness on this particular muggy sunny day even reflected a degree of hypoglycaemia and starvation? At this time the new queens will indeed mate, often quite close to the nest, unlike honeybees which fly some height to engage in their nuptial flight. Some time later the mated queens will take themselves off and find a suitable sheltered location in which to hibernate. So in this regard, they are similar to bumblebees. Click here for more on social and other wasp biology. I found a fascinating paper from the 1970’s where counts and estimates of queen wasp production and over-winter mortality were made for both the common wasp, Vespula vulgaris, and the tree wasp. Click here for details. This seemed to reinforce what I’d recently seen.
Whereas honeybee colonies aim to overwinter as a unit and perhaps produce just one or 2 viable new queens and possibly swarms per year, the wasps’ survival strategy is very different. Perhaps as many as 250 queen wasps are produced by the aging queen as the colony begins to collapse in the autumn. However, over winter mortality of these queens may be as high as 99%, so with luck just enough will be around to begin the cycle the following year. And there’s no need to try to find and destroy a previous year’s nest, since the queens always begin anew. A few days later, after bringing a bit more hay in from our high flower meadow, I remembered to go over to photograph the 2 Broad-leaved helleborines, Epipactis helleborine, growing under mature ash trees on the northern field margin. And there was another tree wasp. Perhaps gaining some nectar, or perhaps just resting up above wet grass level.Maybe the fact that honey bees are the only one of this group of insects to overwinter as an entire, though reduced size, colony, indicates that in many temperate regions it’s a riskier strategy than relying on single overwintered and fertilised queens?
The other very fleeting event of the last fortnight has been witnessing a little bit of the annual passage of the Perseid meteor shower, as the earth’s orbit takes it through the trail of dust left behind by the Swift-Tuttle comet, which itself follows an orbit trajectory taking 133 years to complete. Not being keen astronomers we were lucky in being alerted to its presence by seeing a bright shooting star on Saturday night at a friend’s birthday party. Fortunately the peak of activity happened on Monday night, when the clouds parted and between 10.30 and 11.15 I stood out in the yard, under a silent star spangled sky and spotted perhaps 20 shooting stars over this period. Many coming out of the North Eastern sky around the Perseus constellation which gives the meteor shower its name. One of the many long exposure shots even seemed to capture a faint trail, though frankly the images with no trails were just as glorious with the multi coloured pin points of light from the myriad of stars. We are indeed fortunate to live in a rural area with such minimal night time light pollution. Visiting friends, and a game of croquet, dinner and discussion about holding a mothing event in September, did however persuade me to switch on our 11 watt external light after they’d left, and then get up early to see what was resting up on the wall.
Try doing this on a regular basis and unless you’re up at the crack of dawn the birds will remove everything. But strangely, even when stranded on the backdrop of white washed stone and sticking out like the proverbial sore thumb, after just a single occasion like this the marooned moths seem safe. Perhaps the numbers of these beautifully camouflaged insects are such that in a single season, the resident birds don’t quickly associate these aberrant, bilaterally symmetrical, (usually a give-away of an animate form) splashes of colour on a plain background, with being a breakfast treat. Anyway, I’m glad I decided to leave the light on, since there was a pristine example of a moth I’ve never seen before, and which therefore doesn’t feature in my garden moths pages on this blog/website. It had a particularly striking vibrant green colour, and turned out to be a Scarce Silver-lines, Bena bicolorana. I took a few photos on the wall, and then thought I should improve on these and moved it to a greener foliar background. But where was my patience from years ago, necessary to take all my lovely moth images?
After a few attempts with no success, the moth had warmed up enough to decide it was time to move on and took off flying up over the slated roof. At this point I dreaded seeing it picked off by one of the many swallow mouths patrolling the Gelli airspace, but maybe they’d had their fill earlier in the morning? It disappeared beyond the house and hopefully reached the sanctuary of vegetation for the rest of the day, like this Magpie moth, Abraxas grossulariata, spotted on our track side later in the day. But several other moths have appeared around doorways in this warm, and often muggy, summery weather.A soggy worn, Elephant Hawk Moth, Deilephila elpenor. Buff Arches, Habrosyne pyritoides.Probably (!) a worn July Highflyer, Hydriomena furcata. And even caterpillars have been making a bid for the sanctuary of indoors – this one returned immediately after being removed.Another first has been the number of froglets and toadlets, encountered during day to day gardening activity. In spite of the otter inflicted toad carnage reported earlier in the year in our ponds. Perhaps we now even have a resident greenhouse amphibian? All surely signs of the increasing diversity which just ‘happens’ with the passage of time and benign neglect or minimal interference in a garden or landscape. And finally from the garden:Lovely Hydrangea sargentiana.My favourite of many Dahlia merckii seedlings which I’ve grown, which have already flowered in this their first year.Rosa ‘Grouse’, a delightful plant for growing over a wall, but a briefer flowering period than usual this year, thanks to the abundant pollinating insect population.