When most of us think of pollinators, the European Honey Bee (Apis mellifera) comes to mind first – and with good reason. These hive bees work industriously in agricultural fields and orchards. And we benefit from the fruits, vegetables and of course flowers they visit. According to MSU Extension, though, they are active in temperatures above 60 °F and prefer clear, sunny, placid weather. In case you haven’t noticed (or don’t live in Michigan), that’s not yet our weather here this year.
Luckily, native bees and hoverflies come to our rescue, and the rescue of countless wildflowers. Bumblebees (genus Bombus), our chunky native bees, only require temperatures above 50° and will fly in wet, dark and windy weather – the kind we’re living with this year! And along side them are other native bees and the ever-present hoverflies who look like bees but aren’t. So let’s see who’s out and about in our parks pollinating plants on these cool, damp days of early summer.
[A Disclaimer: I’m a learner when it comes to insect identification, but I’ve done my best to figure out what I’m seeing. Let me know in comments if you think I’ve erred. And if you’d like more detailed info, check out my two main sources: a fine book by Heather Holm entitled Pollinators of Native Plants and this excellent web article by Jason Gibbs from MSU Dept. of Etymology.]
Native Bees Happily Take on the Job of Spring Pollination
Female bees of all species carry most of the load when it comes to pollination, because they feed pollen to themselves and their young. Some species stash it on hairs or in pollen baskets on their hind legs. Others let it spread thickly across the stiff hairs of their abdomen. Wasps, like Yellow Jackets or Hornets, can look like bees but they don’t collect or eat pollen. (They are predators who keep insect numbers in check, including some garden pests.) So if you see lots of yellow or orange pollen on the leg or abdomen of an insect, it’s a bee! Where are these bees finding pollen now?
Native Wild Lupine (Lupine perennis) rises elegantly within the restored prairie at Charles Ilsley Park in early June. Look for them near the observation deck at Gallagher Creek Park as well. They are a popular stop on the pollen route for our native bees right now.
A Metallic Green Sweat Bee (genus Agapostemon) found the Lupine blossoms irresistible. These very small bees are solitary; they don’t live in hives. Instead, they make tunnels in bare soil and tend their young alone. Sweat bees are occasionally attracted to human sweat on hot, dry days but their sting is not as severe as a bee or wasp. They are normally docile while foraging but can be aggressive if you get near their nests. But please don’t use pesticides on them. These little bees do a lot of pollinating! Creating a spot of bare soil on your property away from your garden and house where they can nest will make both you and them feel safer.
One cool afternoon, I watched a couple of sweat bees make the proverbial “beeline” for the native Daisy Fleabane (Erigeron annuus), a close relative of asters and daisies, but a different genus. These tiny, sun-faced flowers are one of the first blooms to emerge in spring and they last all summer. So it seems that the two sweat bees heading in from the right on the photo below know a reliable source of nectar and pollen when they see one!
A native Bumblebee (genus Bombus) used its long tongue to reach inside the lavender lips of the Lupine blossoms at Gallagher Creek Park and then flew off with its pollen load tucked neatly into the pollen sacks on its legs. According to author Heather Holm, bumblebees sometimes use a technique called “buzz pollination” in which they release pollen from tight places by clinging onto a plant’s anthers (the tip of the male stamen that holds the pollen) and activating their flight muscles, making a buzz. Poof! Out comes the pollen. Neat trick. (Click on photos to enlarge; hover cursor for captions.)
Carpenter Bees (genus Xylocopa) shape their nests by patiently shaving off wood bit by bit to make perfectly round holes, usually on the underside of branches, or at our house, under deck railings! They lay their eggs inside, sealing each egg in separately with neat plugs of pollen to keep the young larvae fed. Later, the young bees will overwinter in these nests to emerge for mating the following spring. Here’s what I’m quite sure is an Eastern Carpenter Bee (Xylocopa virginica) nuzzling a Blackberry blossom (Rubus allegheniensis). It looks a lot like a native Bumblebee, but its abdomen is shiny black instead of fuzzy and it has a dot in the center of its yellow thorax.
The blackberry bush also hosted another bee. I believe it’s a Masked/Cellophane Bee (genus Hylaeus). These solitary bees are the only ones that transport pollen in a crop like some birds do with seed. These bees use exisiting cavities in wood for nesting, and wrap their larvae in a thin membrane that evidently gave them the name “cellophane bees” – and they also have white patches on their heads, hence the “masked” name.
Native Golden Alexanders (Zizia aurea), an early summer flower, attracted the attention of another native pollinator, the solitary Leafcutter Bee (genus Megachilidae). They can be very active within blossoms, making what some sources describe as a “swimming motion.” Evidently, that also releases a lot of pollen that they carry on stiff hairs on their abdomen. Their nests are built vertically in hollow plant stems or other natural cavities. They neatly cut and then chew bits of leaves to line each cell. Entomologists suppose that the leaves may preserve the moisture in the pollen plug at the end of each cell, so it will last until the larvae hatches to eat it. The larvae then pupates, emerges for a short life of a few weeks and starts the cycle again.
And then there are the “Wannabees”
I love Jason Gibb’s term “wannabees” for the ubiquitous Hoverflies – also called flower flies – members of the genus Taxomerus (family Syrphidae). Hoverflies visit flowers frequently and are commonly mistaken for bees. Many of them mimic bees and wasps, being patterned in white, black and yellow (or orange). But they differ from bees in one important way; hoverflies do not have stingers. They just want their predators to think they do! They feed on both pollen and nectar. Though hoverflies don’t carry as much pollen on their smooth bodies as bees do on their fuzzy ones, they may make up for that by visiting flowers more often. As a result, they are considered the second most effective plant pollinators. Another great benefit of hoverflies is that their larvae eat aphids like crazy, much like ladybugs do. So they can keep plants healthy as well as do some pollinating.
Drama Unfolds on Daisy Fleabanes!
It’s not a surprise that the nodding stalks of Daisy Fleabane (Erigeron annuus) show up in every field in the spring. Hoverflies move constantly from one to the next since not many different wildflowers bloom in this cold spring! As they land, of course, they drop pollen on the waiting stigmas of the flower, just what’s needed to produce more Daisy Fleabane. From my observation, the flowers in bright sunlight get more attention from hoverflies than those in the shade. Perhaps they see in ultraviolet like bees and the flowers look much more inviting in the sunshine?
But more than just pollination is taking place on those sunny little blooms! It turns out that a Daisy Fleabane can be a stage for high drama – birth and death among the petals! One tiny fleabane flower featured the mating of two hoverflies while a third ignored them in its avid search for a good meal. The dispassionate female seems to be casually having a snack as well.
And on another Fleabane blossom, an ambush! I’ve just learned about Crab Spiders (genus Thomisidae). These crafty arachnids don’t spin webs. They simply sit on or just under the edges of flowers waiting to grab unwary insects. Those long curved front legs do look a bit crab-like!
The Bluebottle Fly (genus Calliphora) in the photo below seems to have been oblivious to a crab spider until it was grabbed around the middle by one of the long legs of its hidden predator. Those big fly eyes look vaguely shocked, don’t they? The hoverfly on the blossom above seems unconcerned, its head deep in the pollen. And what I think is the green sweatbee flying in may choose to do the same on a different bloom. I doubt they stayed around long enough to be a second and third meal for the spider!
What about the Butterflies?
Well, butterflies are arriving, or hatching or coming out from under bark after overwintering. But not many are present yet. And let’s face it; the flowers available now are not especially tempting when compared to the variety and plentitude of summer. So the butterflies that appear in the parks make do with other food sources – sweet tree sap, rotting fruits from last fall, carrion, even occasionally the nutrition left in animal scat! Here’s a selection of the butterflies I’ve seen so far and not one of them was pollinating a flower! (Click on photos to enlarge; use pause button for captions.)
I’ve also seen three different Monarchs but they didn’t stop to have photos taken. And the very tiny White-striped Black moth (Trichodezia albovittata) is a first sighting ever for me. Its miniscule black and white wings flutter so fast that when flying, it looks like a blurry signal of dots and dashes! I was so happy when it paused for a few moments!
Native Plants + Native Insects = Caterpillars + More Well-fed Bird Hatchlings
You’ve probably noticed that I’ve used the word “larvae” several times in this piece. The common term for these squiggly young is “caterpillar.” Caterpillars (as I’ve mentioned before) are the preferred food that birds stuff down the tender throats of their hatchlings. They are great baby food for birds, full of protein and fat and easy to swallow.
So let’s be glad that our native insects are out gathering pollen for two reasons. Our bees and wannabees keep the wildflowers (and eventually fruits and vegetables) reproducing year after year. But by also feeding pollen to all those larval bees and flies, they feed the young of clever birds who winkle them out of holes and pluck them off of leaves and limbs. Yes, we may get a few cut, chewed or even defoliated leaves in our garden. But many of those caterpillars will nourish the next generation of glorious birds singing the morning chorus! Now doesn’t that make you appreciate insects just a wee bit more?