Is your garden mulching habit destroying essential bee-nesting habitat? Many native bee species around the world make their nests in the ground. Have you buried some alive?
Teddy bear bee, Amegilla bombiformis. Photo Louise Docker
About 70% of the world’s bees are solitary ground nesters, not the hive and honey making type that we usually think of. Australia’s blue-banded bee (Amegilla cingulata) and teddy bear bee (Amegilla bombiformis) and many American and European bees, such as the widespread Andrena species, often called digger or mining bees, make their nests by digging tunnels into soft, exposed soil.
Tawny mining bee nest, Andrena fulva. Photo Sarah
Female bees find an area of bare but shaded soil and begin their excavation, creating a series of small, separate chambers in which they lay their eggs. The female bees return to their nests after foraging for pollen and nectar to line the chambers with a food source for the newly-hatched larvae.
So what happens when you cover all your bare garden soil with a thick layer of mulch? You might be protecting plant roots with a cosy blanket, but you’re also probably destroying native bee habitat or, even worse, entombing newly emerging bees which are unable to dig their way out of through mulch. As most solitary ground-nesting bees tend to nest near each other and are also short-lived, you could be wiping out a significant population with one much application.
Ground-nesting bees are mostly either stingless, or have a stinger that’s rarely able to penetrate human skin, so they aren’t dangerous to humans. Their tunnelling behaviour can help aerate soil. Many ground nesting bees are also oligolectic, meaning they collect pollen from only a few different plants, so reducing these bee populations could endanger some important pollination tasks, especially for native plants.
So before you completely cover your garden with a thick layer of mulch, give a thought to the habitat of these important bee species.
Oh no, Catherine! :-(((
Will have to reconsider my programme in the native section of the garden! But too late for now, unfortunately.
Yes it was a shock to me too! I’ve got lots of blue-banded bees which love my pink pentas flowers. I’d never realised that my garden mulching might be doing them out of nesting sites.
I’m really curious having read this article as I have a lot of areas in my garden where I have been thinking “why am I suddenly getting so many ants nests” but I haven’t been seeing ants. Now I’m wondering are these native bee nests? I do have a lot of flowers and also a native bee hive (courtesy of my local council) in my garden. I’m keen to put out more of my home made compost and wonder if this will affect the bees. I don’t actually see a single hole in these excavations, they are flatter and slightly larger than I interpret your picture.
Hi Sue, The photo shows a tawny mining bee nest, a ground-dwelling bee that’s found in Europe and America but not in Australia. You can see a pic of an Australian blue-banded bee nest here http://www.aussiebee.com.au/bees-in-houses.html . If you live on Australia’s east coast then the nests might be ant nests as the ants lift their eggs etc above the extra groundwater resulting from our recent east coast low.
If you send me a photo to info@GardenDrum.com I’ll see what I can find out for you.
Hi Catherine
here is an article on how to create mud brick homes for these gorgeous little creatures
http://www.aussiebee.com.au/aussiebeeonline008.pdf
Sandra
That’s a terrific idea Sandra, thank you!