Saturday, September 23, 2023

Insect Hotel gleanings...


Insect Hotels Attract Beneficial Insects

Beneficial insects support biodiversity, the foundation for the world’s ecological balance. An insect hotel in your garden will attract these beneficial insects, offering them a space where they can propagate and hunker down for the winter. Encouraging biodiversity in the garden helps to increase ecosystem productivity.

Placing an insect hotel in the garden increases the chances that beneficial insects will naturally visit your garden. Also known as bug hotels, bug boxes, and bug houses, these human-made structures offer several benefits. In addition to their decorative qualities, they help supplement the increasing loss of natural habitats.

Although altered and heavily landscaped gardens can be beautiful, they often lack enough of the natural habitats needed to attract beneficial insects and encourage biodiversity. Placing insect hotels in your garden offers optimal bug real estate – the right kinds of habitats to attract these beneficial insects, increase their numbers, and reduce the need for pesticides, since these bugs offer biological pest control. A balanced ecosystem provides numerous benefits not just for the individual garden, but for the environment as a whole.

Benefits of Insect Hotels

  1. Supplement the increasing loss of natural habitats
  2. Encourage beneficial insects to help control pests
  3. Stimulate biodiversity and ecological balance in the garden
  4. Offer an opportunity for educating children about how balanced ecosystems work

Natural Pest Control

Welcoming beneficial insects and pollinators into your garden reduces or eliminates the need for pesticides. Poison kills weeds and pesky insects, but poison is not selective: it kills beneficial insects as well.

According to the USDA’s Natural Resources Conservation Service, three-quarters of the world’s flowering plants and roughly 35 percent of the world’s food crops depend on animal pollinators to reproduce, with more than 3,500 species of native bees helping to increase crop yields. By some estimates, one out of every three bites of food we consume depends on animal pollinators like bees, butterflies and moths, birds, bats, beetles, and other insects.

Insect Hotels: Purchase or DIY?

Different insects require different accommodations in which to thrive. Do a little research about the climate in your area before you decide what kind of insect hotel to buy or make. Each bug habitat performs a different function depending on the location’s climate. In cold climates, they offer a refuge for hibernation, while in warmer climates they function as dry nesting places during the wet season.

While there are many varieties of insect hotels available for purchase, building your own can be a relatively simple, fun, and educational DIY project you can do with children. Using a variety of found natural materials, you can build a bug or bee condo perfect for each type of insect you hope to attract.

Solitary bees and wasps seek places to lay their eggs, so they will be attracted to various-sized holes in wood. They also like to hide out in the open spaces in bamboo poles, which you can cut into small pieces. If drilling holes into wood, vary the sizes from 0.2-0.4 inches in diameter so other species will also fill those spaces. Not-so-nice wood works too: wood-boring beetles love rotting logs.

Reclaimed and repurposed materials such as old pallets, drilled logs, hollow bamboo poles, cardboard tubes, egg cartons, small stones, pieces of concrete and tile, pine cones, pieces of bark, found twigs, dead and rotting wood, hay, plant stems, and discarded planters are some of the kinds of materials that are perfect for constructing a habitat for your garden’s pollination and pest control workforce.

Where to Place the Bug Hotel

A bee hotel needs to be a high-rise to keep away ants, which love dining on bee larvae. Other bug boxes require sheltered but sunny spots surrounded by a variety of flowering and insectary plants (plants that attract and harbor beneficial insects).

Designers from all over the world have created insect hotels that double as works of art. Who knows, maybe you’ll be inspired to build a better insect house – and if all else fails, there’s always ready-made housing you can gift to your bug friends.



Countless gardening stores and home furnishing stores sell insect hotels. Numerous blogs and websites have step-by-step manuals on how to build one yourself. All units are aesthetically pleasing which motivates well-intentioned buyers into adopting the concept. However, these insect hotels are often badly designed and they offer unsuitable home to the target insects. The warning sign of such designs is the unnecessary use of pine cones, glued snail shells, wood shavings and clear plastic tubes. Too many off-shelf insect hotels or build-your-own websites do not come with clear guide on maintenance, which is very important in ensuring the survival of the insects we intend to host.


Large insect hotels (aptly called insect condominiums) using wooden pallets are becoming very popular as individual or community gardening projects, sometimes to include non-insects such as frogs, toads and hedgehogs. In contrast, natural insect habitats occur as small separate nests, and large insect hotels pose risk of disease and parasitism to the insects inhabiting in high density inside. In fact, Rosita Moenen [1] observed that increasing number of badly-designed artificial nesting sites contributed to higher loss of (solitary) bees by parasitism.

Parasitism happens when kleptoparasites lay their eggs in tubes or cells occupied by bee larvae. Their larvae will hatch, consume the stored pollen and kill the bee larvae inside. Examples are parasitic wasps Melittobia acasta and Coelopencyrtus sp., and parasitic fly (Cacoxenus indigator) that attack red mason bees [1]. Insect hotels (especially large ones) make it very susceptible to parasitism. [1][2]. When not managed, the parasites will end up spreading to the rest of the insect hotels and will continue on for following seasons. In similar note, mould brings diseases to insects. It grows when moisture condenses and gets trapped in plastic materials [3] used in insect hotels as tubes and blocks. Lack of good roof/shelter on insect hotels, risking constant exposure to rain also contributes to mould growth.

Here is the right approach to insect hotels:

  1. Insect hotel or insect refuge? Start by thinking which type of insect you wish to host. For example, in the Netherlands, [4] only three types of bees are tube nesters, namely red mason bees (Osmia sp), leafcutter bees (Megachile sp) and bell bees (Chelostoma sp). These bees occupy only small tubes between 2 mm to 10 mm in diameter. For majority that are ground nesters such as bumblebees, mining bees, plasterer bees (also known as silk bees in Dutch) and many types of beneficial wasps, an insect refuge is a more effective approach instead.


  1. Be realistic – small is better: Assess your area where you plan to set up your insect hotel or refuge. Think small and have multiple units housing one species rather than a single large one that attempts to host an entire zoo, requiring potentially conflicting environments. For example, hosting frogs and toads require humid environment with partial shade, while bee hotels need to be dry and in full sun. After you gain experience, you can build and create a different unit for another species.
  1. Choose responsible design: There are a number of good guides online written by entomologists and wild bee experts. Marc Carlton [3] and Werner David [5] have written extensively on right designs for bee hotels, in English and German respectively. For non-bee hotels suitable for lady bugs, lace wings and non-migrating butterflies, Melanie von Orlow[6] has written a book with detailed manuals, available in Dutch and German.


  1. Build your own, build it right: Sourcing your own materials gives you peace of mind that your insect hotel is made of natural, untreated wood and without chemicals such as varnish, paint and wood protectant that will repel insects. To promote sustainability, consider using recycled or natural materials from your garden. If tubes are drilled into blocks, tubes should be smooth without splinters. Good insect hotels should be built sturdy with solid back and roof/shelter to protect from rain.
  1. Install it well: For example, bee hotels [3] must be positioned in full sun, facing south east or south, at least a metre off the ground, with no vegetation in front of it obscuring the entrances to the tunnels. It must also be fixed securely to prevent shaking and swaying from wind. 
  1. Maintain and clean: This is the most overlooked part of having insect hotel. Taking care of insect hotel is just as important as building one. For example, bee hotels [3] should be inspected at the end of summer to remove and clean dead cells. This will prevent mould and mites that would multiply on the dead bees or larvae. Some experts recommend bringing occupied insect hotel into cool dry area such as garden shed during winter to protect the overwintering inhabitants from wind and rain.[3] Without timely maintenance and clean-up, a once-occupied insect hotel may not attract a new batch next season.
  1. Replace when it is time: Insect hotels can degrade naturally after two or more years because the material used is untreated. Change the nesting blocks or parts every two years to avoid build-up of mould, mites and parasites overtime.

Tips to make your garden an insect refuge:

  1. Create sustainable nature: To encourage insects, especially pollinators, grow beneficial plants that that provide nectar and pollen. Choose native species [6][7] such as Lysimachia and Campanula flowers to promote natural biodiversity and avoid non-native plants.
  1. An overly-manicured garden is not a refuge: Some non-migrating butterflies such as Papilio machaon overwinter as pupae attached to plants, so refrain over-trimming during autumn and spring [6]. Look out for ground nests of mining bees, bumblebees and beneficial wasps (German wasps and common wasps) before mowing or mulching your garden. It is easier to protect existing ground nests than to artificially create one.


  1. Limit or no use of pesticides: Using pesticides (such as insecticides, fungicides and herbicides) will be counter-effective as it not only repels away or kill beneficial insects already living in your garden, it also disrupts the natural balance of a local ecosystem. Practise good housekeeping and maintenance so that you will never need to rely on pesticides in the first place. If such need arises, seek environment-friendly remedies or consult professionals instead.


Friday, September 8, 2023

Working Day 3! ~ 8/9/2023 ~ rubbish collecting/moving/keeping, nightshade pulling

We started to notice that the nightshade growing on the left side of the garden were beginning to really take over - forming a bit of a monoculture which was limiting other plant species from growing and establishing. As part of the communal working day we decided to make some choices with the nightshade, removing some of them to open up the bed, and enable the opportunity for others to grow with less competition. 

To begin we started with a rubbish collection moment, finding a multitude of things - a mattress, water hose end, beer cans, pokemon card, even Santa! Again we kept some of the pieces that we could re-use in the future or just took our fancy for whatever reason, though others we relocated to the nearby bin. It's interesting to see each time what objects have moved into this section of the park, it seems to be a huge range, and we question each time what things we decide to remove, what to keep, and in both circumstances why? It's been clear that the private and secretive corner of this garden could easily be used as a sleeping spot, or a hangout point for beers, this leafy green space offering a supportive cocoon to those that seek it. When we remove these pieces of residue, we also remove traces of the ability to use the garden in these ways, but what ways can we try to allow room for them to exist alongside other activities in there, such as a space for adventures for children for example. These are questions we are pondering, for now we removed the cans and sharp objects, the microplastic that are not so nice to leave for the soil, the cigarette butts too. And the mattress that is tossed barely in the garden is moved too, but perhaps it will come back if it was eagerly enjoyed. Let's see.

But back to the nightshades... once our rubbish moving was done we drew our attention to these plants - 

Black nightshade - Zwarte nachtschade - solanum nigrum

In the nightshade family, so related to tomatoes, potatoes and aubergines, all parts of the plant except for fully ripe berries are toxic. Native to Europe, it is now defined as a weed in other countries such as Australia due to its prolific growing habits. An annual or sometimes short lived perennial, it can reach up to 120cm tall, with a 60cm width, growing often with large flat leaves that form heart or toothed edges, their flowers are generally white with a yellow center surrounded by five petals, and they form berries that change to black when ripe (one cultivar in India produces red berries). Ingesting the raw leaves or unriped fruit has been known to result in solanine poisoning (which causes gastrointestinal and neurological reactions), though many varieties exist that have been used as food sources and medicinally for people all over the world.

For more info:

As we did not know specifically what cultivar of black nightshade it was, we were careful when handling it just in case. But it would be great to work out if this type is edible at all.

We tried our best to disturb the soil and surrounding species as little as possible, lifting the plants up with trowels. We decided to only remove what we felt was necessary to provide more room for the other plant species to have more opportunity to establish and flourish, keeping a more balanced diversity in the garden. It was difficult to decide exactly when to stop, when there was enough room, and enough nightshade to also let this species flourish. Through talking and checking in with each other we eventually came to a decision on when to put tools down! The plant species in this section of the garden are mostly plants that have germinated by themselves - seeds sprouting that were already in the soil previously, perhaps blew in somehow, or was sown by someone, human or otherwise. There are also a small amount of plants there that were planted by Rotterdam Gemeente, such as English Ivy. 

We are curious to see how the plants now grow alongside each other with this extra room, particularly as the weather begins to shift from Summer towards Autumn, bringing more rain, stormy conditions and a cooler temperature. 

We placed the plant material into the already existing takkenrillen around the garden before then tucking into a nice lunch in the shade! :)

Here are some photos of the day, from Kate and Silvia >>>

a thistle in amongst the nightshades

but first we need to remove a mattress!

found Santa...

now a spiders home
critters of the garden

finding ways to as carefully and considerately pull up some of the nightshade - with a trowel we wiggled each plant out, trying to limit the impact to the soil and surrounding plants

we encountered lots of worms along the way!

Silvia was cutting the uprooted plants into smaller pieces ready for adding them into our takkenrillen
lots and lots of fruits from the nightshades on the ground afterwards...lots of seeds!

a competition was developed - who found the biggest nightshade!

making space for other species to establish

our souvenirs for the day

Monday, August 28, 2023

some fragments about lead in soil + getting to know the plant species by the playing area of the park (17/08/2023)

 from 'How lead can get into your soil' by the Center for Environmental Health (

<<Lead can occur in soil naturally around a rate between 10-50 mg/kg, but because of past reliance on leaded products, contaminated sites may have lead levels anywhere from 150 mg/kg to 10,000 mg/kg. Although the widespread use of lead had been phased out over the years, lead does not break down over time so it’s still the most common type of soil contaminant in urban areas.

The main ways lead can contaminate your soil is through lead paint or leaded gasoline. Until the 1970s, lead paint was commonplace indoors and outdoors in both residents and commercial properties. It was basically everywhere! As paint ages, it can flake off and leave behind tiny debris that can integrate into soil. Car exhaust from leaded gasoline could have also contaminated soil with lead, especially if the soil was located next to a particularly busy road (2). Even though lead gasoline was phased out in the 1980s, lead can still be present in the soil.

While lead does not bioaccumulate in plants, it does hold very tightly onto clay or organic matter and, unless disturbed, is found in the top 1-2 inches of soil (2). This means that produce that grows lower to the ground, like root vegetables or leafy greens, might be covered in lead-contaminated soil.>>

<<Any result that shows lead above 150 mg/kg means you have high levels of lead in your soil and you should take action before planting and new plants.>>


Getting to know species in shared grounds garden. Species found at the green strip adjacent to the children’s play area:

  • Sycamore

  • Siberian Elm (can grow on polluted soils)

  • Common sowthistle

  • Stinging nettle

  • Common dandelion

  • Common plantain (cat: cua de rata)

  • Creeping buttercup (cat: botó d’or)

  • Ribwort, lamb’s tongue (cat: herba de cinc-nervis) (seeds are critical food sources for songbirds)

  • Persian Ivy (planted by the Gemeente Rotterdam)

  • Horseweed

  • English ivy

  • False spiraea

  • Pale smartweed

  • Black nightshade

  • Fool’s parsley (toxic, in picturethis it appears as not reported in Europe)

  • Coltsfoot (native to Europe, <<the flowers and leaves of coltsfoot have long been used to treat all kinds of respiratory disorders, but its use to prevent coughs and soothe the throat is well documented [...] Coltsfoot has also been used to treat diarrhea, to purify the blood, to stimulate metabolism, to cause diuresis and sweating, and topically as a wound treatment [...] Coltsfoot has been served cooked; raw in salads; fried in batter; to make beer, wine, and candy>> (From ‘Coltsfoot’ by Amanda Dailey and Melanie Johns Cupp.

  • Bitter dock (invasive, used in medieval folk medicine, roots can be used to make yellow-dye)

  • Pigweed

  • Tarragon?

  • Red elderberry

  • American black nightshade

  • Elder

  • Wild garlic?

Sunday, August 27, 2023

Working Day 2! ~ 27/8/2023 ~ more mulch!

Our second communal working day was met with intermingling rain and sunshine! Within the session we decided to lay down some extra mulch to make a more open pathway behind the bed on the left side of the garden, and in front of our neighbour's fence. We clipped back some of the overhanging blackberry too to aid in this. 

We've already noticed a lot of spiders moving into the garden, and they seem to be enjoying the opportunity to spread their webs over this more open section of the garden!

Prunings and organic materials that we took from the garden were formed into another 'takkenril' or in English 'dry hedge', in which lengths of branches and green matter are interwoven between supportive sturdier wooden beams to make a hedge that can be a great safe haven for different species including insects and small animals, whilst also enabling us to keep our clippings onsite to compost over time to the benefit of the surrounding ecosystem.

Guillem prepared a super delicious lunch for after all the hard work in gratitude! - thanks to all who joined!

Here are some pics take by Guillem and Silvia >>>

moving moving!
safety from the rain!

some prunings adding up...



the new takkenril

Tuesday, August 15, 2023



In our first collective working day we experienced what

or how much a pile is  We did so by distributing 25 cubic meters

of mulch that were delivered by the Gemeente Rotterdam, to mark the

walking path through the garden. One pile of mulch, two wheel barrows,

two shovels, one fork, many hands, lunch, water and time.

A green path/tunnel in Charlois.

soil samples from the garden at the back terrace of Rib

About trying to get the soil of the garden tested to check levels of lead...

Notes after call with soil testing laboratory Alcontrol Laboratories:

  • Soil samples have to be delivered to their lab

  • They work with soil testing company Van der Helm

  • They do not generate a report, they just deliver the results of the analysis

Notes after call with soil testing company Van der Helm:

  • They work with the municipality of Delft

  • The process they work with is the following: 1) Client defines border fo the area to be tested 2) They make an offer in regards to the surface of the area 3) They take soil samples on location (they make 2 m deep and 10-12 cm wide holes on the ground) 4) They send the samples to Alcontrol Laboratories for analysis 5) They make a report with the results from the analysis.

  • An estimation of 3.000€ to get the garden tested. Working with Van der Helm is out of the question.