Who is really pollinating your backyard in B.C.?
I have been promising this post for a long time now and apologize for the tease, but it’s involved research and so, here it finally is!
This family has been getting down and nerdy over bugs for the last couple of months. Our bug-whispering toddler continues to cradle invasive stink bugs, I have been traipsing around cut-blocks looking for ants, and Jakob has been taking photos of pollinators in his mother’s wild and beautiful garden.
Now if one of us were to get an award for being the most interested in bugs it would definitely be Jakob. He picked up a Human Bot Fly in South America a few years ago and almost brought it to full term in his right arm (I won’t scar you with those photographs in this post but I might write up a blog in the future about it, with a warning of course).
But I think it’s fair to say that regardless of our level of knowledge we are all into the tiny critters.
When you think of pollinators it's fair if you might only think about bees. Global warming has altered their behaviour, and habitat loss or fragmentation paired with pesticide use and disease is putting hundreds of species at risk of extinction.
As pollinators of agricultural crops and other environmentally and economically important plants, humans are right to be concerned about them. They are important.
But pollinators include all sorts of insects (and bats and birds to be fair) and there is an incredible variety of solitary bees, flies, beetles, butterflies and even wasps that collect nectar from and visit angiosperms (flowering plants).
So while any campaign to save bees should be applauded, this post hopes to broaden your personal paradigm around who else pollinates, because it’s not all bumble and honeybees.
- Western Leafcutter Bee (Megachile perihirta)
This solitary North American bee collects nectar and pollen for its baby bees. Unlike other Hymenoptera bees, it uses its scopae (dense hairs on its body) to collect and store pollen beneath its abdomen instead of on its back leg baskets like a honey bee would do.
It gets its name from its habit of cutting pieces of leaves with its jaws and stuffing them into above-ground tunnels — often made by other insects or animals — to create an urn-shaped crib for each of its larvae. It belongs to the Megachilidae family (as do mason bees) which means ‘big-lipped’ in Greek.
For a farmer, the pollination productivity of one leafcutter bee on a single crop is equal to that of 20 honeybees, and in a greenhouse, 150 leaf-cutter bees do the work of 3,000 honeybees!
Because they store pollen on their abdomen they drop it more often when they fly around. Some farmers know the importance of these bees and will provide homes for them to nest in, protect them over the winter, and put them out in the spring to do their pollinating business.
To spot one, take a look at a bee in your garden. It might be a leafcutter bee if:
- It looks like a honey bee but its body is black and furry
- it has a large head
- it has pollen on its abdomen instead of its back legs
- the leaves of your rose bush have circular holes in them
2. Purplish Copper (Lycaena helloides)
This common North American butterfly thrives in disturbed sites, and its caterpillars thrive on invasive plants such as Japanese Knotweed, Sulphur Cinquefoil, and Wild Buckwheat.
In southern Canada, gravid females lay their eggs in late spring-summer or fall at the base of plants, or in the leaf litter below. The tiny white eggs overwinter and usually hatch in April.
They (and other butterfly species) have been studied as ecological indicators, providing insight into the health of riparian areas, especially in drier, more arid places like Arizona and New Mexico.
3. Physocephala texana (Thick-headed fly species)
Physocephala texana is a member of the Conopidae family (which means cone-faced).
They resemble thread-waisted wasps and this mimicry may protect them from being eaten by larger insects but it is more likely a trait that allows them to sneak up on other insects so they can pass on their genes.
The adult versions of P. texana use a long proboscis to feed on flower nectar, but like other Conopids, its larvae are parasitoids — a parasite that kills its host — and need a host to develop.
When an unsuspecting wasp, ant, or bee comes to visit a garden, P. texana, tackles one mid-flight, pierces its abdomen, and inserts an egg.
What happens next is astounding!
The larvae not only consume their host but practices mind control.
As the host insect surpasses organ failure territory and gets closer to death the fly larvae tells its host to bury itself underneath the soil. This improves P. texana’s chances of continuing to develop under cover from predators and the harsh winter weather.
This is called adaptive manipulation and is similar to when a tropical fungus infects and programs ants to die while biting onto the edge of a leaf.
This native fly and important pollinator is found in B.C., east to Quebec and south into Mexico.
4. Mexican Grass-carrying wasp (Isodontia mexicana)
This native to North American wasp has taken a page out of the book of non-native insects and is doing well in lands across the Atlantic and has been considered an invasive species in France.
Grass-carrying wasps get their name because they collect and line their nests with grasses and plant material and are cavity nesters that lay eggs in hollow branches or the unused nests of other insects.
Grass-carrying wasps eat nectar and are pollinators. But like most wasps, their larvae feed on paralyzed insects, which for this wasp are primarily grasshoppers. Farmers and keen gardeners may want to befriend this wasp as they may be the only defence during a bad grasshopper year.
Keep your eyes peeled for one feeding on a white or lightly coloured flower.
5. Bicoloured Sweat Bee (Agapostemon virescens)
At first sight, this common, solitary (most of the time) bee is easy to confuse with any non-descript flying insect because of its small size (despite being one of the largest species in the sweat bee family).
But take a closer look; its green metallic head and thorax will give it away. If you look at its body you can determine the sex: white and black stripes = female. Yellow and white = male.
They have “sweat” in their name because they are attracted to human sweat. (The research says this is not true however, I can anecdotally weigh in here from a sample size of 2, that while doing field research in a dry ponderosa pine ecosystem in 35-degree summer heat, our hands and sweat-drenched telescope attracted dozens of sweat bees).
They are ground nesters, and important pollinators in urban cities and grasslands and do well in restored grasslands and gardens with lots of asters (aka. flowers in the daisy family) like sunflowers, dandelions, and knapweed.
So there you are. Maybe you know a little bit more about these important, lesser-known pollinators than you did before.
It is almost November but perhaps next spring you’ll mix up your flower seed collection and resist spraying that wasp or wasp mimic because it isn’t after you, it's just on the hunt for nectar or baby food.
