FEATURE FEATURE Nomada goodeniana. (Andrew Byrne) in our garden every summer. We knew After mating, the female can store sperm that little insects lived inside and we to use as required. We don’t know exactly happily ignored them, but back then I how many eggs one solitary female lays, didn’t know what they were. I now know but we do know it varies from species to they were mining solitary bees (mining species, and that experts estimate it’s a into bare soil to create a small nest) and maximum of 20-25 eggs per female. She that they have one of the most fascinating will purposely use her sperm store to lay life cycles you’ll find in nature. fertilised eggs at the back of the nest, and Solitary bees don’t make honey; and don’t these will become females. At the front, form large colonies with a queen, like she’ll lay unfertilised eggs, which will bumblebees or honeybees. They take one become males. They’re closest to the whole year to pass through a complete life entrance, so that they emerge first and cycle and may only survive as adults for a will be ready and waiting for females once few months. This isn’t long enough for they appear. them to raise their offspring to adulthood, Although most solitary bees prefer to make so the young bees have to fend for their nest alone, some species are more themselves, hence the term “solitary bee”. sociable and like to build their nests in little Male and female adults normally come out groups or aggregations. Some solitary bees of hibernation in spring and the females are called cuckoo bees or cleptoparasites. each make a nest. Within the nest, she This means they steal the nest of another constructs a small number of little cells, solitary bee instead of creating their own. and in each she’ll lay an egg and leave a The female, so-called “cuckoo bee”, enters ball of food that she’s made by mixing the nest of another species and lays an egg pollen and nectar. Once she’s happy that near the pollen food supply gathered by the the task is complete, she’ll close the entire owner. When the cuckoo bee’s egg hatches nest and all the females and the males will into a larva, they kill off the cell occupant die, their job complete. The larvae survive and eat the food supply that’s been left. This the winter, eat the food supply that’s been may seem cruel, but it’s a common left for them, each dining and sleeping in phenomenon in nature. its own single chamber, and emerge the Solitary bees vary in the way they make following spring as adults. Then they try their nests. Most of our solitary bees (62 to find a mate and the cycle begins again. species or 80% of Irish species) make their Osmia bicornis. (Julie Kendall) ave you ever heard of solitary bees? Many people have an affection for bumblebees, but most are totally unaware of the THE SECRET LIFE OF littleH solitary bees out there, going about their business in our gardens, parks and farms. If you’ve not noticed them before, they are a treasure waiting to be discovered. Solitary bees are amazingly good SOLITARY BEES pollinators, have a unique and intriguing lifestyle, and are probably living in your garden without you realising it. In Ireland, we have 77 different solitary Dr Úna FitzPatrick, senior ecologist at the National Biodiversity Data Centre and bee species. If you add our 21 bumblebees, co-founder of the All-Ireland Pollinator Plan, introduces the amazing, this brings the total number of wild bees to little-known world of our solitary bees. 98 individual species. When I was a child, lots of tiny little volcanoes of soil used to appear in the grass 28 Irish Wildlife Spring ‘20 Irish Wildlife Spring ‘20 29 FEATURE Megachile with leaf. Christina Ni Dheaghaidh Andrena cineraria on dandelion. (John Cullen) Megachile centuncularis. (Jimmy Goodwin) 5Grey mining bee, Andrena cineraria (Lill Dunne) nest by excavating a tiny little burrow into CHAMPION POLLINATORS bare soil. It need not be soil; it could also be Bees feed their young on pollen, and the peat, clay or a coastal sand dune – they just adults themselves rely on nectar to provide need a substrate that is stable and free them with the energy to fly from flower to Tawny mining bee Halictus rubicundus. draining. Solitary bees need to warm up flower, collecting this pollen to bring back CAVITY-NESTING on Blackthorn. (Liam Stenson) before they can fly, so they tend to make their to the larvae in the nest. Their entire lives SOLITARY BEES (John Fogarty) nests on south- or east-facing slopes, but are dedicated to this, which makes them by The mason bees are in the genus Osmia. In some will nest on bare areas of flat ground far our most important insect pollinator. Ireland, we have two different species. The or within your lawn. When it comes to bees, solitary species are gold-fringed mason bee (Osmia aurulenta) is a The others (15 species or 20% of our Irish “pollinators extraordinaire” – oddly because gorgeous little coastal dweller. It only lives species) are cavity nesters. This means they they are less good at collecting pollen! on sand dunes, where it makes its nest in an need an existing cavity in which to nest. The Honeybees and bumblebees have empty snail shell! The red mason bee (Osmia most commonly used are holes in dead wood, evolved to be extremely efficient at bicornis) usually nests in loose masonry or hollow stems or crevices in loose masonry. collecting and transporting pollen. They in bee boxes. It’s a super pollinator and it’s The bee boxes/hotels you can make or buy store it as a moist pellet on their back legs reckoned just one female can do the commercially are targeting these cavity- (pollen baskets). Most solitary bees have pollination work of more than 100 honeybees. nesting species. also evolved to transport pollen on their The leafcutter bees (Megachile) might be It couldn’t be easier to create a solitary bee back legs, but they don’t moisten it. They the most interesting of all and can be found nest site, and is an extremely useful action pack it into the hairs on their legs as a dry in most habitats. We have five different to take. Three key things to remember are: or loose pellet. This means that more falls species in Ireland. The female cuts out (1) By simply creating small areas of bare off and gets dispersed to new flowers as circular pieces of leaf or petal and flies them soil, you are potentially helping a huge they move around collecting as much as back to line the cells in her nest. Watching number of species. they can. The mason and leafcutter solitary them at work is nothing short of a joy. These (2) Bee boxes can be useful, but are only bees haven’t evolved to store it on their are the solitary bees most likely to use a bee targeting a very small proportion of our back legs at all. The underside of their box. You’ll know your box is occupied if you solitary bees. If you put up a bee box, it abdomen is very hairy, and they pack the see a little piece of leaf closing off the should be the size of a blue tit bird box pollen into these hairs. As you can imagine, entrance to cavities. in the same way that many birds feed their vigorously defend clumps of favoured Solitary bees need to – any bigger, and it will attract predators as they move around, pollen goes The white-faced bees (Hylaeus) are tiny; young. They are found in most habitats and flowers and will intercept and chase away warm up before they and be more likely to harbour disease. everywhere, making them great pollinators they are not much bigger than your little make their nest in hollow stems or reeds. any other insect that enters its territory. These should be placed about 1.5-2m of plants. Not so good for them, of course, fingernail. We have four different species in The wool carder bee (Anthidium However, he does make an exception for can fly, so they tend off the ground in a sheltered south- or as it does mean they have to make many Ireland. They are black and almost hairless manicatum) is a new arrival. It was first females, who he allows to visit the flowers, to make their nests on south-east-facing location. more trips! and resemble flying ants with yellow or white spotted in Ireland in 2015 in Wexford and and it’s here that mating takes place. Wool south or east-facing (3) The most important thing to remember markings on their faces. They don’t carry since then has been happily expanding in carder bees need hairy plants like lamb’s is that solitary bees are very small and Within the mining and cavity-nesting pollen on their back legs like most bees, or the south-east. It’s another very interesting ear or woundwort, as they collect the hairs slopes, but some will don’t fly very far. Nest sites need to be groups of solitary bee species, there is a on their hairy abdomen like the leafcutter character! This one is a large bee (8-12mm), to bring back to line their nests.