It is one of life’s great sensory pleasures. Running your hand through a herb and inhaling its distinctive aroma. Many of us grow herbs for that reason alone, and as many again plant herbs purely as a cooking ingredient. But there is another excellent reason to grow herbs – as pollinators’ food.
Thyme
Herbs have a few advantages over conventional flowers in your garden. This is especially so if you don’t have a lot of space. You might feel you have to compromise on garden thrills, but herbs do well in containers and window boxes and offer a fantastic, colourful alternative. They also, by and large, thrive in drier conditions, thus the often potentially arid environment of a pot or container suits them well. So what’s not to like? Herbs guarantee heady smells, handy cooking ingredients, low maintenance, lovely textures and colours, and of course pollinator food.
You might be persuaded to go down this route but hesitating over which herbs to plant. Well the list is fairly impressive, and there is bound to be something to suit almost every taste. Oregano, mint, chives, borage, fennel, rosemary, lavender, thyme, lemon balm …
Thyme is a proven versatile flavour – an excellent garnish on many foods. A reliable and robust little herbthat will return year on year, it is ideal for filling in cracks in a pavement or rockery. It is often used in meat, vegetable and fish dishes.
Sage is a mainstay of many a risotto dish, and who doesn’t like a sprig of rosemary in roast potatoes. To run your hand through a rosemary plant and then inhale is one of life’s great pleasures. The blue flowers are a bee magnet.
Chives, with their vivid purple pom-pom flowers, are another summer classic. They spruce up many a salad and go particularly well with the ever reliable potato.
Chives
The blue flowers of borage are pleasantly distinctive and those small flowers suit bees with short tongues. It is one of the best flowers for bumblebees. If yellow is your colour, then the chances are you are familiar with fennel – mining bees and honeybees are drawn to it in good numbers. You will be amazed at how popular fennel is with hoverflies.
There is more to mint than meets the eye. Spearmint and peppermint are well known and strong flavours. The smell from even the gentlest rub of this plant is a delight and a unique aroma. It’s a favourite element in a host of summer drinks.
Lavender is probably the most photographed herb. Vast swaying seas of this attractive blue flower are the classic picture-postcard vision many associate with Provence in the South of France. If you stumble across a lavender field, be prepared for a knock-out smell and the gentle hum of thousands of bees. These blue oasis are as much a pollinator’s dream as a nature-lover’s feast.
Lavender in Provence
You would be right it you think that I mention the Mediterranean with some longing. As we head into summer, it has a pull of its own and herbs are a big part of the experience. If you follow the sun in Europe then the chances are you will encounter herbs on your travels. If you go a little further south, to Morocco say, you might enjoy mint tea which is part and parcel of Moroccan culture. In Greece, Tzatziki relies on mint for flavouring and may come as a dip or a sauce. Back in Provence, your food experience has a strong chance of including the ever popular blend of herbs known as Herbs de Provence.
Home or away, there is a lot to enjoy in the world of herbs. And if you plant some around your doorstep you will be helping our hard-pressed pollinators big time. Don’t, whatever you do, be persuaded by culinary experts to trim your herbs before they flower – that would not go down well with your local pollinators.
Once upon a time, so Charles Perrault (1628-1703) told us, a prince was out enjoying nature by merrily killing animals in the woods, when he spotted a hidden castle deep in the forest. The prince’s myrmidons explained that the castle housed a beautiful princess who had been cursed by an evil fairy; the young lady was to lay in a comatose state until awakened by a handsome prince. His Highness, who obviously had a high opinion of his looks, decided he was the person destined to break the spell. But getting to Sleeping Beauty wouldn’t be easy; the castle was surrounded by trees and a formidable obstacle that would have stopped a less determined hobbledehoy: a wall of brambles.
Having princely clothes ruined by brambles. The Sleeping Beauty, art by Arthur Rackham (1867–1939), Wikimedia Commons.
Brambles or blackberries comprise many species that are difficult to tell apart; over 300 of them have been recognized in the UK. These related species are known as micro-species, and for practical reasons they are treated collectively as a species complex or as an aggregate group (abbreviated as agg.). So we usually refer to brambles as Rubus fruticosus agg.
Natives to much of Europe, brambles are valued fruit crops when grown as blackberry varieties, but they are also invasive in some circumstances. Their dense thickets are barriers to amorous princes and roaming livestock, and their thorns hurt animals and contaminate wool. Thanks to their vigorous growth (watch their shoots thrusting ahead), brambles can outcompete other wild plants and curtail the development of tree saplings; if left unchecked, brambles can quickly alter the species composition and physical structure of some habitats. For those reasons, they are considered invasive weeds in Australia, New Zealand and the USA.
But as we have learned from many a definitive self-help book, problems are opportunities with thorns on them: several birds and small mammals nest or take shelter in bramble scrub. And their berries are food for sundry animals such as badgers, field mice, foxes, moths and voles: watch some of them having a nutritious fruit breakfast. Bramble berries are quite handy when other sources begin to dwindle in late summer and autumn.
But brambles have much more to offer; their open, bowl-shaped flowers, typical of the Rosaceae family, are easily accessible and produce large amounts of pollen and nectar, which are available during most of the season – usually from May to September in the UK. So a range of pollinators and other insects take advantage of these abundant and reliable food sources, from the European honey bee (Apis mellifera), which is one of the most enthusiastic visitors, to scarce species such as the brown-banded carder bee (Bombus humilis) (Wignall et al., 2020).
Brambles have a flexible approach to reproduction. They commonly propagate vegetatively (no seeds are involved) by deploying ‘runners’, shoots that take root when they are touching the ground; they can resort to apomixis, which is the production of seeds without fertilisation; or less frequently, they can use the familiar sexual mechanism of pollen deposition. This diversified strategy helps explains brambles’ complex taxonomy. Plants generated by vegetative growth or apomixis are clones, genetically identical to the parent plant. When they do occasionally outcross and produce seeds from fertilized ovules, the resulting offspring will have genetic profiles slightly different from the parent plant. Given time, these variants become species marginally different from each other, which spread out as clones and readily hybridise (Clark & Jasieniuk, 2012). Untangling these species is a job for a small tribe of patient, dogged taxonomists dedicated to batology (from the Ancient Greek báton, ‘blackberry’): the scientific study of plants in the genus Rubus.
Although infrequent, sexual reproduction is important for maintaining brambles’ genetic diversity, and here insects play their part by cross-pollinating plants. Among brambles’ many flower visitors, several bees and flies have been considered candidates for the job. But this list is biased because it leaves out insects we don’t normally see collecting pollen or nectar – the nocturnal visitors, i.e., moths. And they should not be neglected. Like many other plants, brambles produce nectar with variable concentrations of sugars during the day, and their highest output happens to be from late afternoon into the evening. Such sugary bounty wasn’t likely to go unnoticed by the night shift wanderers. Anderson et al. (2023) reported a range of visitors to brambles flowers during the day (flies and bees, mostly); but at night, moths were almost alone in dropping by for a sip of nectar. But there was more; moths visited fewer flowers per hour than diurnal visitors, but they deposited more pollen grains on stigmas. That’s an important finding. Flower visitation is often – and incorrectly – associated with pollination. In fact, some visitors avoid pollen altogether, or manage to remove the pesky yellow grains from their bodies. Pollen deposition is a well-tested method to evaluate who is pollinating what.
So here we are. Blackberry lovers notwithstanding, brambles are generally despised components of our flora, even though they play an important part in supporting pollinators and other animals. These brambles’ customers in turn may depend on secretive moths for the sexual reproduction of their hosts. As is often the case in nature, the plot is considerably thicker than it looks.
Charlotte Rankin is our guest blogger today. Charlotte works as a Conservation Office for Buglife Scotland and leads on the Pollinators Along the Tweed project.
Pollinators Along the Tweed, a new Buglife Scotland partnership project enhancing and restoring 40 hectares of wildflower-rich habitat along the River Tweed, is set to create a buzz for local pollinators and communities.
Learning how to carry out FIT Counts at Traquair bioblitz
Working with Scottish Borders Council, Borders Forest Trust and other landowners in Scotland and north Northumberland, Pollinators Along the Tweed sets to create, enhance and restore 40 hectares of wildflower-rich habitat. Working across 50 sites in towns and villages along the Tweed, as well as the wider countryside, this project will help restore habitat connectivity for pollinating insects, enabling them to move across the landscape and adapt to a changing environment.
Part of the Destination Tweed source-to-sea river revitalisation project, Pollinators Along the Tweed is being made possible with funding from the National Lottery Heritage Fund, AEB Charitable Trust, Craignish Trust, Fallago Environment Fund, J & J R Wilson Trust, Milkywire, NatureScot, Northumbrian Water Group and ScottishPower Foundation.
Boosting early flower resources for pollinators at Tweedsmuir
Running from November 2022 to May 2027, the project will enable communities to learn about, protect and monitor the Tweeds’ pollinators. There will be opportunities to join in practical conservation volunteering, pollinator workshops and walks, citizen science activities and more – from meadow bug hunts to school sessions and wellbeing walks. The project also aims to provide additional support to landowners and managers through habitat management advice and workshops.
Since launching in November 2022, volunteers have been busy bee bank building at Peebles Golf Club, seeding margins of wetland scrapes at Border Forest Trust’s Corehead, and boosting early season flower availability for pollinators at Tweedsmuir and Norham. With the pollinator season getting underway, an events programme is shaping up with opportunities to get involved in pollinator surveying, identification and family activities. So far, children have got involved in crafting hoverfly lagoons and individuals have learnt how to carry out Flower-Insect Timed Counts, with more events on the way – please contact Charlotte.Rankin@buglife.org.uk if you would like to find out more about upcoming events.
Insects recorded at Traquair House bioblitz
Pollinators Along the Tweed further builds on Buglife’s B-Lines and pollinator projects both in Scotland and England. B-Lines present an opportunity to create a network of wildflower-rich areas, providing essential routes for pollinators to use. The B-Lines network includes our best habitats and identifies key areas to restore and create new wildflower-rich meadows, important grassland verges and pollinator friendly gardens. B-Lines can be adopted by farmers and landowners, local authorities and communities. Everyone who manages land can help to restore our pollinator populations.
If your farm, garden, local park or area is within the Tweed B-Line or wider B-Line network and you would like to know more to get involved, please contact Buglife Scotland at scotland@buglife.org.uk. Find out more about the Pollinators Along the Tweed project by visiting buglife.org.uk/projects/pollinators-along-the-tweed.
Building a bee sand bank at Peebles Golf Club with Peebles Golf Club’s Biodiversity and Ecology Group
The bark louse Echmepteryx hageni (order Psocodea), an obscure fungus-eater from North America, is no more than 10 mm in length. Unsurprisingly, its eggs are miniscule. But these small dollops of nutrients are plenty for the egg parasite Dicopomorpha echmepterygis, a wasp in the family Mymaridae, which are known as fairyflies or fairy wasps. We have little information about this parasitic wasp, but we do know that males are blind, wingless and phoretic, that is, they need to cling to another organism to move about; in this case, females are their ride. Males also have no mouthparts, so they cannot feed.
If you suspect that a male D. echmepterygis shouldn’t expect a long and prosperous life, you are right. He lives off the nutrients taken as a larva from one of his host’s eggs, and those reserves won’t last long. But that’s of no consequence for the male; his only purpose during his short existence is to impregnate a female, which, conveniently, is his means of transportation. He only needs to crawl to the appropriate spot on her body to do the deed. This lifestyle is by no means unusual; many other parasitic wasps have similar traits. But D. echmepterygis males have a unique claim to fame: they are the smallest adult insects on Earth, measuring 139 µm in length (Mockford, 1997).
To have wings and be able to fly, other fairyflies have to be bigger, but not by much: the winged and marvellously named Tinkerbella nana is 250 µm long. We can have a better appreciation of these fragile fairy creatures by considering the hardships of being small – the risk of desiccation, and barriers unknown to larger animals such as surface tension and fluid viscosity. Michael LaBarbera’s The Biology of B-Movie Monsters is a highly entertaining and illuminating discussion on the physical limitations of body sizes. For a deeper exploration, D’Arcy Thompson’s underappreciated classic On Growth and Form is a tour de force of the physical properties acting on biology.
There are many fairyflies besides D. echmepterygis and T. nana: over 1,400 of them. And these are the known species; certainly the true number is much higher. All described species are egg parasitoids (their young develop on or inside another organism, eventually killing it) of a range of insects, and they are good at finding their victims: some fairyflies parasitize eggs embedded in plant tissue, buried in the soil and even submerged in water.
Fairyflies belong to one of the many families of Chalcid wasps or chalcidoids (superfamily Chalcidoidea). This is an enormous group of about 22,500 known species, although the total could reach over 500,000 (Noyes, 2019). Most of them are small (less than 3 mm) parasitoids of different life stages of many insects and arachnids (spiders, mites, scorpions and others).
A great number of insects and other arthropods have to live with the high probability of bumping into a chalcidoid wasp, but that’s not the half of their problems. Around 25,000 species of Darwin wasps, or ichneumonids (family Ichneumonidae), and some 17,000 species of braconids (family Braconidae) join forces in a vast army of parasitic wasps – and again, these figures are likely to grossly underestimate the real number of species.
As the story goes, J.B.S. Haldane (1892-1964), British/Indian geneticist, evolutionary biologist, mathematician and more, found himself in the company of a group of theologians. On being asked what one could learn about The Creator from studying his creation, the atheist Haldane is said to have answered ‘an inordinate fondness for beetles.’ Haldane may have said something of the sort, and indeed a Celestial Big Cheese would be seen as partial to the order Coleoptera. With nearly 400,000 known species, beetles lead the biodiversity table, comprising about 25% of all animal species (excluding Bacteria and bacteria-like Archaea). But there is strong bias here: beetles are popular and relatively easy to find, while most parasitic wasps are very small, hard to identify, and tricky to handle and preserve in collections. It’s a lot of work, and there are not many specialists in the area. But the more they look for parasitic wasps, the more beetles’ predominance is challenged. Most holometabolous insects (those with four life stages: egg, larva, pupa, and adult) are attacked by one or more hymenopteran parasitoid, sometimes five or even ten, although we may not know their identities. By modelling parasitoid-to-host ratios for some groups of insects, Forbes et al. (2018) estimated that hymenopterans easily beat beetles in the biodiversity league. Some coleopterists may not like to hear that.
Parasitic wasps are practically everywhere; just in one suburban garden in Leicester, England, Owen et al. (1991) collected 455 species of Darwin wasps, some new to the British list, in a two-year period. These wasps have an enormous sway in the structure and composition of biological communities. They limit the numbers of insects and spiders, and by keeping herbivores in check, they have an indirect but vital influence on the diversity and abundance of plants. Naturally, pollinators are not immune. It goes without saying that the nature of our flower-visiting assemblages is shaped by parasitic wasps.
We can gauge the regulatory power of parasitic wasps by their efficacy as commercial biological control agents. For example, Encarsia formosa is one of the most efficient weapons against whiteflies in glasshouses, while Anagyrus lopezisaved cassava crops from the ravages of mealybugs in Africa and Asia.
LaSalle & Gauld (1993) estimated that at least 50% of the 150,000 or so species of Hymenoptera are parasitoids. They all have the alarming habit of eating their hosts from inside their innards while they’re still alive, which seems execrable and cruel. Darwin was dismayed by it, as he expressed in a letter to his friend Asa Gray in 1860:
‘I am bewildered.— I had no intention to write atheistically. But I own that I cannot see, as plainly as others do, & as I shd wish to do, evidence of design & beneficence on all sides of us. There seems to me too much misery in the world. I cannot persuade myself that a beneficent & omnipotent God would have designedly created the Ichneumonidæ with the express intention of their feeding within the living bodies of caterpillars, or that a cat should play with mice.’
Despite Darwin’s misgivings, parasitic wasps are not particularly shocking, considering that approximately 40% of all known species are parasitic (Dobson et al., 2008). And these tiny, fragile agents of doom are just a fraction of many others such as viruses, fungi, protozoa and worms, who have an array of imaginative ways to cause sickness, suffering and ghastly deaths. Haldane’s god, so fond of beetles, also has a kinky sense of humour.
But such anthropomorphic considerations are misguided. Parasitoids, parasites and predators are regulators of the natural world. They prevent excessive population growth, including of agricultural pests and disease vectors, and remove the old and sick from the general population. Parasitism helps shape biodiversity and ecosystems, so it is not intrinsically bad or good. It is a characteristic of life on our planet. It is as it is.
‘Morality is a subject for philosophers, theologians, students of the humanities, indeed for all thinking people. The answers will not be read passively from nature; they do not, and cannot, arise from the data of science. The factual state of the world does not teach us how we, with our powers for good and evil, should alter or preserve it in the most ethical manner’ (Gould, 1982).
‘We entomologists, who have no charismatic elephants to hide behind, no cuddly panda bears to hug before the public, no aesthetic whooping cranes, no passion-inducing spotted owls, no thousand-year old forest giants – we entomologists are at the forefront of the biodiversity battle with only our bugs for a shield’ (Grissell, 1999).
Scottish pollinators 