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Sara-Jane & Alica at Virens Studio

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Weeds & Pests in the Garden: A New Perspective

Jan 20, 2023

It’s always good to take a step back and see the world from a different point of view. So why not put aside cultural perceptions and traditions to view our gardening foes with fresh eyes?


In this article, let’s take a relaxed look at some common weeds in a way. Exploring, why we don’t like them, what benefits they can bring and also a few interesting facts about each.


As always, keeping in mind that every green space has its own advantages and challenges and each stakeholder, their own needs and desires. Good design and maintenance always starts with a strong foundation of knowledge. Finding what works in your space and what the priorities and parameters are. That includes what thresholds are best for your garden. It pays to do some research and have a good idea of how to monitor weeds and pests; deciding what actions are best to take if thresholds have been reached.

Snails and Slugs (Gastropoda)

Why don’t we like them
- They leave large, ragged holes in tender leaves and flowers.
- Slugs leave traces of silvery slime.
- They can decimate seedlings leaves completely, leaving just a stem.


Eco services
Slugs and snails are scavengers, they quickly clean up dead and damaged organic material that may not otherwise break down (they are not picky eaters!). And although they’re low on the food chain, they are a vital part of it. Gastropods eat worms, maggots and larvae. And transversely, they're also a source of food for snakes, toads, turtles, birds and even hedgehogs.


slug anatomy
Anatomy of a slug, Carlo Pollonera (1889)

Slugs and snails are all gastropod mollusks, of which there are thousands of species. Snails have shells, while slugs don’t.


Gastropod eyestalks are specialized tentacles. In some species, they are retractible and will even regrow if severely damaged.


Slugs can infiltrate soil up to a meter (40inches). They require moisture to stay healthy, which is why they come to the soil surface in wet conditions. The slime that they produce coats their bodies and prevents them from drying out while also providing a track for them to glide along.


There are many medieval manuscripts that feature knights facing off against slugs and snails, and nobody knows why. Often appearing in the margins, the scenes have been found in 70+ volumes. Could they be a meme from medieval times?

medieval snail
Man vs. snail, Brunetto Latini’s Li Livres dou Tresor (c 1315-1325)

Aphids (Aphidoidea)

Why don’t we like them
- Aphids damage plants by sucking the sap from leaves, twigs, stems, or roots.
- They can spread plant diseases.
- Many aphid species produce large amounts of "honeydew," a sweet sap that makes leaves and objects in close proximity shiny and sticky.


Eco services
Aphids provide food for a huge range of beneficial insects and beetles, including lady bug larvae, predatory midges and parasitoid wasps, lacewing larvae, rove beetles and hoverflies. Having some aphids can help to balance an ecosystem by attracting and increasing a diverse population of beneficial bugs that will build balance in the food chain.


Out of 4400 aphid species only 250 are pests.


Ants have been known to offer aphids protection in order to feed on their honeydew. And interestingly, some plants have adapted to produce "pearl bodies" (full of lipids, carbohydrates and proteins) that can temp ants to switch allegiances; protecting the plants instead.


Aphids generally attack vulnerable plants and only harm healthy ones in large densities.


They produce pheromones to warn their kin when they are attacked. Which has been utilized as control agent against them.

Ant collecting honeydew
Ant collecting honeydew
pearl bodies
Pearl bodies on a Cissus leaf
Aphids for dinner
Lady bug larvae approaching a meal of aphids

Mosquitos (Culicidae)

anatomy of a mosquito
Anatomical sketches of the mosquito (1904)
benefits of mosquito netting
The benefit of sleeping under a mosquito net. Chromolithograph by A. Guillaume.

Why don’t we like them
- They bite.
- They can spread deadly diseases, including Zika virus, West Nile virus, Chikungunya virus, dengue, and malaria.


Eco services
Mosquitoes pollinate flowers and are in fact, the only pollinators of certain orchid species. They help keep things clean, feeding on insect carcasses and waste products (including algae, microbes and honeydew). All the while adding nutrients like nitrogen, to the ecosystem. Their voracious appetite can act as a biological control agent, managing other insect populations. While on the opposite end of the food chain, mosquitoes and their aquatic larvae support a wide range of wildlife from fish, dragonflies and turtles to bats and birds. This includes hummingbirds, which rely on small flying insects as a primary food source.


Out of the 3,600 species of mosquitos, only a small fraction bite humans. And within those few species, it’s only the females that are producing eggs that require blood.


Mosquito’s have learned to trick ants into sharing their food. When a mosquito inserts its mouthparts into and ant’s mouth and strokes its head, the ant will regurgitate some honeydew.

There's a tiny crustacean that's showing great promise as a biocontrol for some mosquito species. These copepods (a type of zooplankton) bite continuously as they paddle their way through the water, killing 30-40 mosquito larvae a day. Research is ongoing.


The name, mosquito, is Spanish for ‘little fly’.

Mosquito mask
Mosquito mask, Tlingit (artist unknown),(pre 1843)


Why don’t we like them
- They suggest an unkempt garden or lawn.


Eco services
Mushrooms are evidence of larger fungi, that function as decomposers. Their powerful enzymes make fast work of debris, clearing up a variety of dead and dying material, including wood. The mycelium that create mushrooms, provide a network through which plants share information, nutrients and resources. Their filaments help to extend the reach of plant and tree roots creating resilient communities. Depending on the species of fungi, many mushrooms are an important source of food and medicines.


Mushrooms are not a species in themselves, they are actually a single part of larger fungi; like a flower on a plant.


Out of the estimated 1.5-5 million species of fungi on the planet, only 20,000 fruiting mushrooms have been identified so far.


Fairy rings start at the center and move outwards as the mycelium seek nutrients. There are around 60 species of fungi that have been known to form mushroom rings on the soil surface. In northern France there is a single fairy ring that is 300m (980ft) in diameter, thought to be 700 years old.


Fungi are a powerful, if slow, ally in bioremediation. They can absorb hazardous chemicals, heavy metals, radioactive materials and even plastic from contaminated soil and water.

Toadstools, Mushrooms, Fungi, Edible and Poisonous: One Thousand American Fungi, by Charles McIlvaine (1900)
fairy ring
A fairy ring of mushrooms

Moss (Bryophyta)

Why don’t we like them
- They suggest an untidy garden or lawn.


Eco services
As generally small, non-flowering plants, moss are often overlooked, but they are an invaluable part of many ecosystems. Their huge surface area works to soak up and hold rainfall, protecting and bringing moisture to the underlying soil. Simultaneously hosting a huge diversity of beneficial bacteria and micro-organisms. Mosses also play a vital role in the development of new ecosystems, they are one of the first plants to colonize areas with little to no soil, providing the conditions for soil to form. Moss can influence soil climate, nutrient cycling, and vascular plant germination.


There are more than 12,000-25,000 species of moss.


Their extensive surface area allows them to absorb toxins from air.


Moss gardens have been cultivated in several cultures, perpetuating a feeling of calm, stillness and age. Because the specific conditions to grow moss are extremely difficult to recreate, they also give a sense of the greater area in which they exist, simply because they cannot exist in every space.


Moss has long been utilized as bedding and insulation, especially in cold climates. In coastal Canada, Indigenous people have used moss to clean fish and smoke foods like salmon and camas bulbs.

A variety of mosses, Ernst Haeckel (1904)
Mossy stairs
The famous mossy stairs of Myōhō-ji, Kamakura, Japan


Compared to cotton, Sphagnum moss has the ability to absorb liquids (3x faster), plus hold and distribute them more evenly. They also have antibacterial properties, which led to their use as bandages as recently as the First World War.


a piece about the size of a muffin, would harbor a 150,000 protozoa, 132,000 tardigrades, 3000 springtails, 800 rotifers, 500 nematodes, 400 mites and 200 fly larvae. These numbers tell us something about the astounding quantity of life in a handful of moss
-Robin Wall Kimmerer

Dandelions (Taraxacum)

Why don’t we like them
- They spread easily.
- They make gardens and lawns appear unkempt.


Eco services
Dandelions can be an important food source for beneficial insects in areas where flowers are scarce. This plants strong tap root also helps to break up and add nutrients to lean compacted soils. In fact, if you see dandelions congregating in a specific area it’s a good indicator of soil conditions. Additionally, all parts of the plant are edible and many of them are used in herbal remedies, teas, salads and even dyes.


There are 30+ species that can claim the common name of Dandelion.


Their tap roots can infiltrate soil to depths up to 4.5m (15ft) just take a look at the drawing in the Wurtzelatlas.


The name, Dandelion, comes from, ‘dents de lion’ (lions teeth), due to the shape of its leaves.

dandelion tea
Dandelion tea, Korea

Wasps (Vespidae)

Why don't we like them
- They sting and can cause allergic reactions.


Eco services
Wasps are voracious predators of insects that can be destructive including grubs, greenfly, caterpillars and weevils, spiders and even roaches. Some farmers use wasp colonies as pest control; their appetites can match those of birds, mammals and amphibians. The short lifespan and fast reproductive cycles of wasps mean that they can match population fluctuations in their prey.


There are 30,000+ species known as wasps, including many that are solitary and a few that are so tiny they are microscopic.


Mud-dauber wasps (Sceliphron) build clay nests that are rich in essential minerals, including iron, zinc and calcium. These are sometimes consumed by populations in Africa, who refer to them as, "Insect earths".


Some orchids have evolved to mimic female wasps. They use pheromones to trick male wasps into pollinating them.

micro wasp
A tiny wasp on a clover bloom
wasp and aphids
Braconid wasp with aphids

Clover (Trifolium)

root nodules
Nitrogen fixing root nodules
crimson clover
Crimson Clover (Trifolium incarnatum)

Why don’t we like them
-They give the perception of a poorly kept garden or lawn.


Eco services
Clover like many legumes, form nodules on their roots that host nitrogen-fixing bacteria (rhizobia). The two elements exist together in a symbiotic relationship, until the plant dies and the nutrients are released into the soil. This process makes clover a great choice for green manure or living mulch. It also works to protect bare soil from erosion and retain soil moisture, while reducing weed populations. Similar to dandelions, clover can be vital source of nectar for pollinators in areas that lack flowering plants. They also provide fodder for livestock and wildlife from birds to bears. Clover is edible and can be used in herbal remedies, teas and also as a vanilla-like flavouring.


There are 300+ species of Trifolium.

Recently, research was able to demonstrate that clover plants warn each other via the network of runners that link them. If one of the plants is attacked by caterpillars, the other members of the grid are warned via an internal signal. Once warned, the remaining plants strengthen their chemical and mechanical resistance.


Four leaf clovers may be considered lucky, but there are a rare few that have been found with five or even six leaflets. In fact, a remote Arctic area with an abundance of these multiples has led to much speculation. Are they due to genetics, environmental conditions or a combination of both? Further research is ongoing.


Folklore surrounds clover, Druids believed that carrying a clover allowed one to see harmful spirits which gave the bearer time to escape them. Which may have led to clovers being seen as a lucky plant that brought good fortune and offered protection.


wild garden
A brilliant sign at Radwell Meadows, UK

Hopefully you've had a bit of fun and picked up a few interesting facts that may, or may not, influence your gardening choices this year. Happy Gardening!


When we work with nature instead of trying to impose our will, the solution is often found within the problem.
-David Holmgren


-Sara-Jane & Alicia at Virens Studio

Virens is a studio located in Vancouver, Canada, that specializes in Ecological Planting Design, Urban Greening Consultation and Garden Writing. Please get in touch today, and don't forget to follow us on social media.


© Virens Studio 2023 (all photos are used for demonstration purposes and do not necessarily belong to us.)


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