Not long ago I thought the only bees which existed in this world were honeybees and bumblebees. Then, when I learned that there were actualy many other species, I looked harder around me and discovered an astonishing variety of bees of many sizes, colours and behaviours, and all that right here, in my backyard! Here are some of them, little sweat bees!
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| Sweat bee (Lasioglossum Dialictus) on strawberry flower |
The smallest bee in my backyard is just 5mm long. It's a Lasioglossum Dialictus, tiny black sweat bee with metallic green shine, easily mistaken for a fly. I was thrilled when I discovered their nesting colony among the patio bricks in my backyard. The patio is sunny and the soil among the bricks is sandy, making it an ideal site for these ground nesting bees.
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| Lasioglossum Dialictus and nest holes |
Though solitary, these bees make communal nests, where many bees share one site, while each bee digs her own nesting tunnels to lay eggs (they might even share the tunnels, I'm not sure). New bees emerge from these eggs early in the spring next year, males first, right around when first dandelions start blooming. I'm trying to find out which native plant could serve as an early nectar source for these bees, but for now, I'm letting dandelions flower, despite the reproachful look I imagine my neighbours might have if they peek over the fence (I try my best not to let them go to seed...)!
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Lasioglossum Dialictus males can be seen early in the spring on dandelion flowers,
most often the only nectar source at this time
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As soon as our plum, pear and apple trees start flowering, tiny Lasioglossum females start collecting pollen that will serve as food for developing bee larvae. Since these bees are so small, they have a short flying range, and thus require forage sources to be within a few hundred meters from their nest.
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| Lasioglossum Dialictus female collecting pollen from a plum flower |
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Lasioglossum Dialictus female, carring a load of pollen
to her nest hole hidden in the moss between bricks |
Another small sweat bee of Lasioglossum spp. I often see in my backyard is Lasioglossum zonulum. This bee is a bit bigger than Lasioglossum Dialictus, but still less than 1 cm long and frequents flowering fruit trees as well as some other small flowers in spring.
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Lasioglossum zonulum on radish flower
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| Lasioglossum zonulum and honeybee |
By the way, according to the report published in the journal Science, wild bees are twice as effective at pollination compared to honey bees! Here is the link for the report:
Sweat bees of Halictus spp. are another species of ground nesting bees that visit our flowering fruit trees in spring.
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| Halictus rubicundus is about 1 cm long |
Green sweat bees (Agapostemon spp.) are the most striking of all sweat bees. Females are solid shiny metallic green in colour, while males have distinct stripes on their abdomens. They are active throughout the year and prefer composite flowers.
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| Green Sweat Bee (Agapostemon spp.) female |
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| Green Sweat Bee (Agapostemon spp.) female |
Late in the fall, when not much else is flowering, asters are important food source for these, and many other bees.
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| Green Sweat Bee (Agapostemon spp.) male on Aster spp. |
80% of our native wild bees, including the sweat bees, are nesting in the ground and habitat loss is one the major reasons for the decline wild bees seem to be experiencing. That is why I make sure to leave parts of the ground in the sunny sites uncovered (no mulching), I always check the ground for nests before I dig (I dig or disturb the soil rarely anyways). And of course, I never, ever spray any pesticide, organic or non organic, anywhere!
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