In the spring of 2019, I wrote an article about the so-called “wasp garage,” prompted by the fact that these things started appearing in many supermarkets and pet stores. Lots of people bought them, put them out in their gardens—and nothing happened. NGOs and local governments also installed them in public spaces, and there are even a few in the National Botanical Garden in Vácrátót—how should I put it—moderately successful. At Pünkösdfürdő, however, I saw some that were nicely inhabited, and the one at the Budapest Zoo has also been populated (although it’s poorly assembled).
Success requires two things: knowledge and patience. Installation should be done by the end of March or early April. Choose a dry spot protected from rain and wind. A good nest contains holes 3–9 mm wide and 5–15 cm deep in reed or wood. Pots, bricks, pinecones, small wooden pieces, and straw are only for human amusement—they’re unnecessary. Bricks made of fired clay with holes may serve as holders for reed stems (but not by themselves), while lime-sand bricks (like Ytong) and aerated concrete blocks are completely unsuitable, as their high water absorption can cause the whole thing to rot.
Holes larger than 9 mm are rarely occupied by insects. Which smaller holes they use depends on the species. The mason bees (Osmia bicornis, in Hungarian: kőművesméh) prefer 5–7 mm holes, so provide plenty of those. The alfalfa leafcutter bees (Megachile rotundata, in Hungarian: lucerna-szabóméh) like smaller ones, and European orchard bees (Osmia cornuta, in Hungarian: szarvas faliméh) prefer larger holes, so offer a variety of sizes.
Tubes should be closed at the back, which is why bamboo is ideal—you can cut it at the node. Hardwood works too, but don’t drill through it—blind holes are needed. Softwoods are unsuitable because they crack, and pines also contain resin. Pinecones are also useless; their strong resin smell might even repel insects.
The attached pictures show a cradle I made with a 3D printer, which has acrylic tubes inside. It’s been successful for years. They just finished filling it yesterday. You can open it to observe insect development. If you make something like this, ensure the tubes are closed at the back and that the box seals light-tight when closed. If outside light seeps in, the insects will not occupy it. Also, never use solvent-based adhesives or varnishes when making a bee hotel. Any surfaces insects touch—like the wood containing the holes—must not be varnished at all. The outer cover can be treated with a water-based outdoor varnish.
Orientation matters when installing. Insects don’t like north-facing openings. Ideally, the entrance should face south or southwest and be about 1.5 meters above the ground. Ensure enough free space in front of the holes for flying insects. It’s best if the “wasp garage” isn’t in direct blazing sun—place it in a somewhat shaded spot. And by the way, the “garage’s” residents aren’t wasps but bees, so “bee hotel” is a more accurate name.
Dangerous honey bees
Wikipedia says, “Most bees are social insects forming colonies.” Well, folks… nonsense! Science recognizes about 30,000 bee species (only 2,000 in Europe), and only about 5% of them form colonies—the rest are solitary.
When people hear “bee,” they immediately think of the busy honeybee producing honey, propolis, and other wonders from pollen and sweet plant nectar. Honeybees live in colonies of 40,000–80,000 individuals organized into castes, ruled by a single queen. As many of us know, they’re quite irritable. Near the nest or water sources, they can be easily provoked and will attack. Their sting is more dangerous than that of wasps—even the feared hornet—especially since they often attack in swarms. The sting hurts and swells badly. As a child, I once got stung on the palm because I grabbed a garden tap handle where a bee was drinking from a leaky seal. My hand swelled so much that you couldn’t tell front from back, and I couldn’t bend my fingers. Grandma applied a vinegar compress, and from then on, I left the tap alone.
These days, hysterical parents would call an ambulance or rush to the ER. Such parents ought to be slapped hard—they waste emergency services needed for real cases. The child might be allergic to a bee sting, but even then, there’s no need to call an ambulance. Either not yet—or too late. By then you might as well need a hearse…
Here’s the thing: less than 1% of children are allergic to bee stings (about 3% of adults). The body produces histamine in response to bee venom, which causes the swelling—this is a normal and useful reaction. If the body produces a lot, that’s still not an allergy; the discomfort can be reduced with an antihistamine cream or tablet.
If the child is allergic, they will go into anaphylactic shock in about 15 minutes: cramps, vomiting, difficulty breathing, fainting—in the worst case, death. In such cases, the only thing that helps is an immediate adrenaline injection into the thigh. After that, you can (and must!) call an ambulance. Without adrenaline injection, by the time the ambulance arrives (or Dad reaches the ER with the kid—after running over a pensioner, two preschoolers, a cat, and maybe a truck on the way), it won’t matter anymore.
Instead of panicking, it’s smarter to find out whether the child is actually allergic to bee stings. If so, venom immunotherapy can eliminate the allergy for life. It’s not convenient—it takes 3–5 years of medication based on insect venom. But after that, they’ll be safe for the rest of their life, even when Mom is no longer around to freak out at the doctor.
The best way to avoid a sting is to avoid bees—or, if you encounter them, don’t provoke them. Don’t wave your arms or try to swat them. Running away won’t help either—they can fly at 40–45 km/h, which means they could easily overtake any Olympic sprinter.
Apart from honeybees, some bumblebee species (Bombus) also form colonies—around 200 individuals, much smaller than honeybee hives. Bombus terrestris (white rump) nests underground, often in abandoned mole tunnels; Bombus lapidarius (yellow rump) in stone piles or tree hollows. They can sting too, but are peaceful—you’d have to be very stupid to provoke one.
Lonely bees are not dangerous!
Most other bee species are solitary—even many bumblebees, like the Arctic bumblebee (Bombus polaris). The so-called “wild bees” (95% of bee species) are extremely diverse, from 1.3 mm tiny species to 3 cm giants. Many are specialists, linked to specific plants. “Wild bee” isn’t a scientific category—it’s just what people call any bee that doesn’t make honey. Mining bees dig nests in soil; mason bees use walls or plant stems; leafcutter bees cut pieces of leaves to line their nests.
The most likely guests of a bee hotel are mason bees, especially Osmia cornuta and Osmia rufa. These species are not aggressive—you can often handle them without being stung. Problems only arise if they get trapped in clothing. They work on the brood cells for about three weeks, stocking them with pollen and nectar. Unlike honeybees, they don’t have pollen baskets—the pollen is carried on dense hairs under their abdomen. Each female makes about 25 trips to gather enough pollen, visiting around 75 flowers, pollinating them along the way. She can even control the sex of the offspring. Each hole typically holds 2–3 males and 1–2 females, separated by partitions, sealed with mud.
After the nests are filled, nothing happens visibly for almost a year, until the next March. You could move the hotel if it’s in the way, but better not, as temperature and humidity matter. Ants may attack if stored in a basement. Recently, I’ve noticed tits pecking at the brood in winter—protect the entrance with a plastic or plywood cover placed 2–3 cm in front of the holes, so it won’t block emerging bees if you forget to remove it in spring.
The development of the larvae is quite slow; pupation only occurs in August. The emerging adult enters diapause during the winter, a resting state in which it almost completely suspends its vital functions. This period is quite risky for them, as they are exposed to the weather. If the winter is warm, they don’t rest enough and burn through their fat reserves too soon. If the cold lasts too long, they starve to death. If spring warms up too early and there are no flowers yet, they may emerge prematurely and starve as a result. In a fortunate case, diapause lasts until the beginning of the vegetation period.
At the end of March or early April, the hatched bees chew through the clay plug and begin their independent lives, which lasts roughly until early summer. During this time, they mate, build new brood cells, lay eggs, and the cycle starts all over again. Right now, there’s still a lot of activity around the bee hotel, but most of the reed stems are already occupied. Anyone thinking of setting one up now is probably too late—there’s a good chance the first residents won’t arrive until next year. Don’t expect a big buzz of activity in the first year; it usually takes one or two seasons for them to settle in, as females from previous years return.
Alongside mason bees, leafcutter bees (Megachile centuncularis, in Hungarian: szabóméh) may also appear. They line their brood cells with carefully cut pieces of leaves. A single hole can contain a dozen cells arranged in a row. The larvae feed on the pollen and nectar provided by the mother, just like mason bees, wall bees (Megachile parietina), and bumblebees do. Our guests may also include predatory wasps. Unlike bees, they do not collect pollen; instead, they place paralyzed crickets, spiders, and other insects—immobilized by their venomous sting—into the brood cells. The larvae feed on these helpless but still-living creatures.
Killers in the Nest
Dazzlingly beautiful chalcid wasps (Chalcididae, in Hungarian: fémfürkészek), cuckoo bees (Coelioxys sp., in Hungarian: kakukkméhek), and bee flies (Bombyliidae, in Hungarian: pöszörlegyek) may also appear. The brood cells of bees are not always the scene of a happy childhood—sometimes what happens inside is more like a horror movie. This is because there are brood parasites, such as cuckoo bees.
Cuckoo bees do not build nests and do not collect pollen (they can’t, as they lack the special hairs needed for that). They wait for the nesting bee to leave its half-finished cell to fetch more pollen, then sneak in and lay their own eggs. The cuckoo bee larva hatches first, starts feeding on the stored pollen earlier, and grows faster, maintaining dominance throughout. The rightful offspring simply starves to death, or the cuckoo bee larva kills and eats it. Sometimes the cuckoo bee female stays in the cell and kills the host larvae—and even the host female.
Nearly fifty cuckoo bee species are known, more than half of which parasitize solitary bees, though some target social species as well. In honor of Sir David Attenborough’s 92nd birthday, Canadian researchers named a cuckoo bee species after the renowned naturalist and documentary filmmaker: Epeolus attenboroughi.
Cuckoo wasps also include parasitic species, some of which lay their eggs directly inside developing bee larvae. Charming bee flies also lurk near the nests, laying their eggs next to the host’s eggs and camouflaging them with grains of sand. Their larvae first consume the stored provisions, then turn on the host larva.
From the solitary bees’ perspective, these parasites are unwelcome guests—but their presence is part of the natural order.
Albert Einstein once said: “If bees disappeared from the Earth, humanity would survive for no more than five years.” As it happens, he was right about this too. One harmful consequence of human civilization’s expansion is that the flowers providing food for bees have declined, and nesting sites have diminished. Agricultural monocultures (like wheat fields) offer no nectar, city lawns are mowed to the ground (because we think that’s what looks nice), and we quickly remove dead wood, dry stems, reeds, brush, and piles of stones (because they’re “ugly”). Sandy and clayey areas are “reclaimed” and seeded with grass.
I don’t really believe that creating bee pastures and bee hotels can seriously solve this problem, yet it’s still a worthwhile thing to do—if only because it makes us feel better. After all, it’s easier to face extinction with a clear conscience…
