Science & Nature

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DRAWN TO THE LIGHT

Angle Shades Phlogophora meticulosa Gillian Nash

Anna Seropiani/Shutterstock

The beautiful angle shades moth may fly in any month of the year, even though its main flight seasons are early summer and autumn. An unusual wing shape and pattern in delicate hues of pink, buff, brown and olive green provides efficient versatile camouflage among the autumn leaves or shadows of summer vegetation whilst resting in daylight hours. Its unique form makes identification unmistakable and a closer look will reveal folds in the wings which further aid camouflage to protect from predators. The nocturnal adult moth feeds on the nectar of flowers such as buddleia, many other open-type flowers and in late summer may be seen by torchlight extracting juice from blackberries and other over-ripe fruit with its long proboscis. Eggs laid by this second generation will hatch to overwinter in the larval stage, feeding when the temperature is above 5˚C.

The night feeding larvae may appear on almost any low-growing vegetation or garden plant, can be seen in any month and is sometimes found in greenhouses, hiding by day among the leaves of overwintering plants. Confusingly, in its final stage of growth the stocky caterpillar can be either brown or bright green but always with a subtle chevron design along its length and a distinct continuous or broken white line on its sides.

Having fully feasted on its chosen leaves, the larva forms a cocoon just below ground level where it will spend the winter – the adult moth of this second generation emerging the following early summer.

Common and resident, numbers can be significantly boosted in some years by migration from Europe, especially in southern counties and coastlines. The angle shades moth can be found in almost any habitat and is frequently seen in both town and country gardens. With first records for Dorset around the 1800s, it seems to have been, and remains, a consistently common species in the county and throughout most of Britain.

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ENERGY EFFICIENT HIVES

Paula Carnell, Beekeeping Consultant, Writer and Speaker

The National Honey Show, somewhat confusingly shortened to the NHS, is held annually in London and is an excellent opportunity to meet and catch up with fellow beekeepers. The 2021 event was particularly exciting as the year previous had to be held virtually. Beekeepers from across Britain swarmed into the capital to ensure the event was a success with competitions for honeys and bee-themed products along with an extensive lecture and workshop programme.

Of particular note was a talk by German bee researcher Torben Schiffer. He, like me, is especially interested in the effect of honeybees in the environment and the impact they have on our native solitary and bumble bee species. He suggested we should have ‘exclusion zones’ around known native bee colonies and a stop to the mass importation and relocation of honeybee colonies. He also advocated a permaculture system for agriculture, banning of agrochemicals, forbidding intensive queen bee breeding, forbidding feeding honeybees with sugar, and, amongst other points, a strictly regulated beekeeping system. I was shocked and of course excited that such ‘revolutionary’ statements could be made during the opening lecture of what is usually considered to be a conventional beekeeping event. I also shared my excitement during an interview with Esther Coles of the Queen Bees podcast.

But the real penny dropper for me was the debate around hive insulation. I have been lucky because I started beekeeping using a WBC hive, which already has an extra layer of outer boxes or ‘lifts’, protecting the hive within from extreme temperatures. As I use more variety of hives, I have become aware of how some colonies absolutely thrive, and others don’t and Torben’s lecture clearly demonstrated the insulation difference between a large natural tree cavity, or log hive, compared with a standard national or Langstroth beehive box. He also shared figures of how much nectar a colony needs per year; an average managed colony needs 225kg of honey JUST to maintain their colony core temperature of 35 degrees.

His team had calculated that the average nectar production from plants between March and October per kg/km squared was 7203kg in extensive landscape, and 4112kg/km squared in intensive landscape (farmland countryside). He then found that energy saved by colonies living in well-insulated hives was from 12 times to 20 times compared with conventional wooden hives.

This has major implications for honey producers. If the bees need to eat less because they are in better insulated hives, not only will survival rates improve, but there will be more surplus honey to share! It seems that the sweet spot for wooden hives is an 8-10 cm thick hive wall which substantially reduces the energy demand on the bees. This would match a tree cavity in the wild, or a heavily cloomed straw skep hive.

He went on to compare the temperatures in full sun-exposed apiaries to those in shade, and again he clearly demonstrated the extra efforts required by bees to maintain a steady, safe temperature. In cities, many hives are placed on roof tops, with little or no shade. He measured the surrounding temperatures on a typical Berlin summer’s day and was astonished that beekeepers would even consider leaving bees in such an exposed position. If the bees overheat, they require more water, plus more bees would be leaving the interior of the hive to help reduce the temperature.

This now influences my recommendations for hives. I have supported clients who choose to have nationals or Langstroth hives, as they are often cheaper because less materials are needed, however, I have now seen first-hand that a well-insulated hive really does support the bees!

This information also emphasises the use of nonwooden hives. Polystyrene hives are common place now, particularly for new or small colonies. As a rule I don’t like polystyrene as it breaks down and is not environmentally-friendly. However, I am warming to the Apimaye plastic hives as seen in action in the humid Cocos Keeling Islands. These hives were designed for use in Eastern Europe and China, and a bee scientist friend of mine in Belgrade has found the bees manage to maintain good, warm temperatures throughout the winter in these longer term plastic hives. Although initially I turned my nose up at them, I’d certainly prefer to see a hive made to last many hundreds of years than a beautiful Western Red cedar felled.

January may feel like a new fresh start, however for the bees it’s a vital time to start preparing for the first spring blooms; keeping themselves warm and being able to move more freely around their hive is vital to their survival. Time to pop out and check your bees are protected and maybe start creating some thicker boxes for the coming season!

GREEN RESOLUTIONS

Peter Littlewood, Director, Young People’s Trust for the Environment

Image: Katharine Davies

Now that the new year is upon us, it’s time to think about some resolutions. Perhaps you’re looking to lose weight, drink less or even plan to actually use that shiny new gym membership for more than a month or two in search of the new you! Or maybe you could make a change or two to benefit the planet. You might already be doing some or all of these, but here are a few ideas to help you make a difference in 2022:

1. Eat less meat. Vegetarian and vegan diets are getting more and more popular, but if you don’t feel ready to give up meat just yet, why not think about having two or three meat-free days a week? In the UK, we ideally need to be eating 70% less meat and dairy products by 2030 to help meet our targets for reducing our greenhouse gas emissions. So maybe in 2022 you could start making that adjustment by eating a little less meat each week.

2. Get to know your local butcher. As well as eating less meat, you can make sure the meat you do eat is better quality. They can provide you with a much wider range of cuts of meat than you can get at a supermarket and will know much more about the providence of the meat they’re supplying.

3. Try to buy more of your fruit and vegetables locally. Supermarket fruit and vegetables have often been produced in faraway countries and have travelled thousands of miles, giving them a massive carbon footprint. Local farmers’ markets are a great place to pick up fresh produce that has been grown locally and hasn’t had to travel great distances.

Gold Hill Organic Farm, Child Okeford

4. Buy less stuff. We live in a consumer society, but our consumption is driving the overexploitation of the earth’s natural resources. Earth Overshoot Day (the day on which we use up all of the natural resources that can be replenished naturally during that year) happened on 29th July 2021 and it’s getting closer and closer to the start of the year. Try to make sure everything you do buy is either useful or beautiful. If it doesn’t meet these criteria, you don’t need it and that brief feeling of excitement you got at the time of purchase will fade very quickly! And remember to check out charity shops and websites like eBay to see if you can get what you want from someone who has already bought and used it, rather than brand new. 2022. If that seems too extreme, try breaking it down into smaller chunks, and commit to not buying any new clothes for a month and see how it goes. If you do end up wanting to buy new clothes, always ask yourself: will I wear this at least 30 times? If you don’t think you will, don’t buy!

6. Learn how to fix your tech. It’s easy to get caught in upgrade cycles for our electronic devices these days, particularly mobile phones. But you really don’t need to have the latest, shiniest version every year. It’s best to hang on to your device until it’s no longer receiving security updates from the manufacturer. Nowadays, that’s typically three to five years. If they stop working, you can often fix devices yourself, with the aid of websites like ifixit.com, which provide step-by-step instructions and photo guidance for doing your own repairs. And when the time comes to replace your tech, make sure you either recycle it or sell it. Each phone, tablet or computer contains quantities of valuable metals and minerals that can be re-used to make new devices, and recycling them means less of the raw materials need to be extracted from the planet.

7. Switch to green energy. It’s easy to switch to a tariff that uses 100% renewable energy. Exactly how they do this varies and you can look for recommendations from organisations like the Energy Saving Trust if you want to ensure that your green tariff is really helping reduce greenhouse gas emissions. You could also look at increasing your home’s insulation or even changing your gas boiler for a green heating option, like an air-source heat pump. Heat pumps are a major investment and won’t work well in older houses, unless you make a lot of changes. But they’re an excellent option for houses that are really well insulated and energy-efficient.

8. Do more to reconnect with nature. Just getting out into the countryside for a walk has great benefits for people. Research has shown that being in the outdoors helps to improve mood, reduce stress and improve your physical health too. We live in a beautiful part of the country. Treat yourself to more time to get out and enjoy it!

If each of us makes a few changes this year, then cumulatively it will add up and make a difference.

PROPELLING OURSELVES TO A LOW CARBON FUTURE

Rob Bygrave, Sherborne Science Café

Propellers are an essential and often overlooked component in the engineering field. Known most particularly for their use in aircraft, both fixed and rotary, they are also found in a large number of other applications. These range from the mundane (e.g. small cooling fans in electronic devices) to large, visible installations (e.g. wind turbines); from applications hidden in hydroelectric generators (e.g. Francis Turbines) to screw propellers used for driving much of the world’s shipping across the oceans.

Impellers, the first cousin of propellers, are very similar components and have similar design constraints. The distinguishing feature is that a propeller converts rotary motion into axial thrust. Impellers, in contrast, are used to create a negative, sucking force as part of a pump.

Because propellers essentially turn one type of energy into another, whether as a generator or as a propulsor, their efficiency has a direct bearing on the planet’s carbon footprint. The plethora of applications for propellers and impellers means that any design or practical improvement in their efficiency will have a very positive, environmental impact.

Jon Fraser, lecturer at UWE Bristol and director at

Jordan Paw/Shutterstock

Start Here: Impeller and Propeller Systems, presented an intriguing and contentious talk at our April 2019 meeting concerning his efforts, over many years, to improve the effectiveness of propellers and impellers. Intriguing because he seemingly offered a relatively easy fix to improving efficiency of propellers and impellers, and contentious because he felt unable, at this stage, to reveal the pertinent secrets of his new, augmented design to an eager audience.

Jon’s career experience had been in industrial design at a government level and in retirement as a keen environmentalist in local politics. His background also encompassed memories of his uncles, as RNLI crew members, versed in the nature of the violent seas of Ross and Cromarty, venturing out in appalling conditions to rescue distressed seafarers. These memories had made him particularly sensitive to the needs of the RNLI for a better propulsion system for their boats. He is also convinced of the veracity of good quality turbines, both as alternative energy sources (wind and tidal) and for use in the developing world, most particularly in healthcare, where a dependable and easily accessible source of electricity is essential.

An audio-visual presentation showed the effectiveness of the new propeller design when emplaced in an outboard motor and tested in the sea at Portland. The propeller demonstrated little cavitation and a tight rod of bubbles showed in the wake of the propeller. Cavitation, a significant issue in propeller and impeller operation, is caused by rapid changes in pressure in a liquid leading to the formation of vapourfilled cavities where pressure is very low. These collapses can generate shock waves which in turn can cause wear, tear or fatigue, especially if cyclic. In a naval context, cavitation in a propulsion propeller creates noise, giving away position.

As speed of the test boat increased, the wake narrowed, unlike that from a conventional propeller. Jon described the contrast between a standard and his augmented propeller as that between a blunderbuss and a sniper rifle. Timed, measured runs had shown a fuel saving of 10%, a better turn of speed and greater stability at full throttle. Dynamometer readings with the boat secured to land, but engine running in the water, showed a 20% increase in thrust. Similarly, in helicopters, his augmented rotors were silent in operation, unlike conventional rotors which whistle, losing energy by cavitation.

Whilst top aerodynamic engineers at AgustaWestland’s helicopters had dismissed his design, the RNLI, Lloyd’s Register and the Wolfson Unit Test Tank were taking the project seriously, as was a major marine engineering company in Southampton (CJR Propulsion). A further twist to Jon’s augmented design provides a tantalising insight into the science of fluid dynamics. Modern fluid dynamics is built on the mathematics of the Swiss mathematician, Daniel Bernoulli (1700-1782). Although the mathematics has advanced considerably since the 18th century, there remains within this body of work the so-called ‘Bernoulli Conundrum’ which has not yet been solved and for which there is a prize of £1M for the first correct solution. Jon had an inkling that his augmented propeller design may provide a lead into solving the Bernoulli Conundrum.

At the time of his presentation industry’s response to Jon’s augmented propeller design was mixed and further test-tank trials were continuing in Southampton. In the field of innovation, it is the case that vested interest, sloth, lack of foresight and general disinterest can kill a new invention which should rightly claim a place within current practice (think: Frank Whittle’s development of jet engine, to name but one example). Jon admitted that these were significant impediments and he was seeking exposure to peer review where an objective, public and critical appraisal of his designs could be made.

If this is truly the breakthrough in propeller and impeller design that Jon believes it is, we will have been privileged at Sherborne Science Cafe that his cuttingedge invention was first raised here!

sherbornesciencecafe.com

___________________________________________ Wednesday 12th January 7.30pm Return of The Great Egg Race This lively competition returns with practical tasks, quiz, refreshments and prizes. All you have to do is form a team (4 members max), register online and join us for a postChristmas science party! sherborne.scafe@gmail.com

___________________________________________ Wednesday 26th January 7.30pm Understanding Epilepsy – Speaker: Professor Roland Jones from Bath University Digby Memorial Hall, Digby Road, Sherborne. From sacrifices and exorcism to cannabis and the human brain in a dish. sherborne.scafe@gmail.com

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