Thank the bees — again

I missed the national day of recognition for Honeybees (Aug 16).  A “wordl” poster created by the New York Bee Sanctuary does a fantastic job of illustrating how much we have to thank the bees for maintaining our food supplies.

Wordls are picture representations of the vocabulary associated with a particular subject. The size of the text is proportional to the importance of the subject for that word. Wordls are easy to create for any article, website, or random group of words using Tagxedo.com

Honeybees pollinate dozens of crop species in addition to a multitude of flowers.   Some, like this red salvia seem designed especially for honeybees — in fact, it’s a bit of a tight squeeze to crawl into the corolla of the flower and down to the nectar source.

A tight fit, but worth it. Always nice to have an exclusive food source.

Wikipedia has an impressive list of crop species dependent on bee pollination, so thank the bees by planting more nectar-rich bee wildflowers in your garden.  You can read more about this here.

Look alikes (… or why mimicry works)

Recently, I have misidentified a few critters in the field, only to realize what they really are when I begin editing them on the computer.  For example,

Not a Monarch Butterfly!  Though this Viceroy looks like one, there is a faint black line on the hind wings that is absent in Monarchs, and Monarchs have many more white spots on the leading edge of the forewing.

Viceroy butterflies tend to be smaller than Monarchs, but this is difficult to determine in the field without both present.  From:  Learner.org

Milkweeds have their own set of orange and black insects, some of which are distasteful, but most of which are simply mimicking the color patterns of the noxious individuals (like the Monarch butterfly).

It’s probably no accident that Box Elder bugs also cash in on this Milkweed mimcry complex, copying the pattern of the Common Milkweed Bug (top right above).  It is also about the same size as the milkweed bug.

Boxelder bugs are considered pests, as they congregate by the hundreds in our window sills in the fall.  (Photo from the National Pestcide Information Center)

And then there is the “bee complex”.  Everyone wants to copy the yellow and black pattern of the bees and wasps, cashing in on the threat of a painful sting.

The things that sting have bright yellow and black coloration; some have fuzzy hair and some don’t — even that pattern is copied.

The mimics might even try to act like their models — hovering in front of flowers (hoverflies) or between perch sites (robberfly)

There are obvious advantages for the mimic — gaining protection from potential predators who have learned that certain color combinations mean distasteful and/or dangerous prey.  So, the nectar-loving, innocuous hoverfly seemingly poses a threat to would-be consumers of these bite-sized flies.  This is an example of Batesian mimicry, where the model is toxic, but the mimic is not.

But in other cases, the mimic is just as distasteful and perhaps as lethal as its model.  Naive Bluejays offered Monarch or Viceroy butterflies (sans wings) didn’t like either one of them and regurgitated their meal.  Many species of bees and wasps similarly utilize the yellow and black warning coloration.  These are examples of Mullerian mimicry, where the mimics and their models are both unpalatable or dangerous.  What is gained with this type of mimicry most likely is reinforcement of the warning to potential predators, who because of one bad experience with a particular individual prey item, avoid anything that looks like that in the future.

There are many websites devoted to this topic; one of the more interesting (from Discover Magazine) can be found here, where you can read about other uses of mimicry in the natural world, like:

“Orchid flowers fool flat-footed flies by faking fungus-infected foliage“

Is this plant diseased? Or is it disguising itself with fungal spots to lure in potential pollinators?  From Discover Magazine blogger, Ed Yong.

Bugs on Blue

The Sky Blue Aster, along with many other aster species, is in full bloom in both woods and prairie landscapes now. And the pollinators are making the most of the little time remaining this fall to collect nectar and pollen.

Syrphid flies (otherwise known as hover flies) are suddenly quite a bit more common on the asters and goldenrods.  I found these two (very large) adult flies foraging on the sky blue asters.  Apparently, these two species are quite often found foraging on the same plants together, and are commonly known as “flower flies”, for obvious reasons.

I think this is a member of the genus Eristalis, a very diverse group composed of 99 species worldwide.  These flies are very generalist pollinators and collect nectar from whatever is blooming in great abundance.  They are so intent on burying their heads in the flower that I never got a good photo of their front ends.

The other “flower fly” was a bit more cooperative, sitting in the bright sun with all body parts exposed.

The longitudinal stripes on the thorax and cross-striping on the abdomen mark this species as a member of the genus Helophilus, named for its sun-loving habit. There are only 9 species of Helophilus north of Mexico, but since they are best identified by examining the genitalia, I am not sure of the species.

Their bright yellow and black (bee mimic) coloration and hovering flight between flowers make them an interesting insect to watch.

Another frequent visitor to these asters was this tiny iridescent green bee, known as a sweat bee for their attraction to salty surfaces.  They can be annoying, buzzing around us to land on slick, sweaty skin, and do sting if crushed while brushing them away.

Of course, the asters were also hosting a large number of wasps and honeybees, all trying to gather in the last products of a long summer of blooms.

How to pollinate a milkweed flower

I read a blog post where someone tried to hand pollinate milkweed flowers in her yard because there were too few bees, and she was concerned she might not get any seed.  Hand pollinating these flowers would be difficult; it helps to have insects do it for you.

The following insects were helping out today in the milkweed patch in the backyard.  In any of the photos, look at the most distal portion of the insects’ legs for pale yellow sacs of pollen attached (e.g., left hind leg of the butterfly below).

Red Admiral butterflies

Bald-faced hornets, handsome black and white wasps related to yellow jackets and who can sting multiple times in defense of their large cylindrical papery nests.

An undentified skipper butterfly, with just one or two pollinia attached to its front legs.

A soldier beetle, not really a good pollinator, but there for the nectar reward anyway.  Supposedly these beetles eat a lot of aphids, so they are good insects to have around.

Lots of these paper wasps, zooming around the plants, and me.  You might think these are yellow jackets, but they have longer bodies, less yellow on the abdomen, and orange antennae instead of black ones.

And this year, for a change, we have honeybees in the garden.  There was quite a bit of competition on this particular bunch of flowers, and neither the wasp nor the honeybee would relinquish their position.  Actually, I think they were stuck, with their feet caught in the milkweed “traps”, where the pollinia reside.

Milkweed flowers are complex.  They have five chambers in which the pollinia are sequestered (black dots in the photo below) that lie in front of five cup-shaped reservoirs of nectar.  (photos from http://www.microscopy-uk.org.uk/mag/indexmag.html?http://www.microscopy-uk.org.uk/mag/artfeb05/bjmilkweed.html)

Milkweed pollinia have a central corpusculum from which two translator arms extend and support the paired pollenia sacs.

STEP 1 of the pollination process:  In the process of exploring the nectar reservoirs in each flower, an insect might slip its leg down into one of the pollinia chambers and get it stuck on the corpusculum.  As it tries to raise the leg to free itself, it drags the entire pollinia assemblage out of the chamber where it remains attached to the insect’s leg while it forages further among the flowers (e.g., the bee in the photo below has several pollinia attached to its right legs).

In STEP 2 of the process, the insect’s leg (with pollinia attached) slips down into the pollenial chamber of a different flower where again it gets stuck, but this time, in raising its leg, one or both of the two pollinia get inserted into the slit that leads to the “egg” or stigmatic chamber.

That may be way more than you want to know about this process, but you can see why hand pollination would be difficult, unless you have really tiny tweezers.

The end result of all of these leg manuevers by the various insects seeking the milkweed’s nectar looks something like this.  The flower in the lower center of the photo and the one at about 10 o’clock have several pollinia sticking straight out from the stigmatic chamber, which means that one of the pair of pollinia did get inserted.

Sometimes the insects get their legs so mired in the slits and clefts in these flowers that they are unable to escape and eventually exhaust themselves and die.  I am happy to report that both the paper wasp and the honeybee successfully got away from the flower traps.