If You’re Out Collecting Sweets, It Pays to Look Scary

Only fools mess around with bees, wasps, and hornets as they collect nectar and go about their business while visiting flowering plants.  Relentlessly curious predators and other trouble makers quickly learn that patterns of white, yellow, or orange contrasting with black are a warning that the pain and anguish of being zapped with a venomous sting awaits those who throw caution to the wind.  Through the process of natural selection, many venomous and poisonous animals have developed conspicuously bright or contrasting color schemes to deter would-be predators and molesters from making such a big mistake.

"Red Eft"
The brilliant colors of the “Red Eft”, the terrestrial sub-adult stage of the aquatic Eastern Newt (Notophthalmus viridescens), provide protection not as a form of camouflage, but as a warning to potential predators that “I am inedible” due to the presence of tetrodotoxin, a strong neurotoxin.  Over the generations, natural selection has better enabled the brightest of the individual “Red Efts” to survive to adulthood and reproduce.  Meanwhile, those efts that provided a less obvious visual clue to their toxicity frequently allowed their pursuer to learn of their defense mechanism by the taste-test method.  As one might expect, far fewer of these latter individuals survived to breed and pass along their more cryptic color variation.

Visual warnings enhance the effectiveness of the defensive measures possessed by venomous, poisonous, and distasteful creatures.  Aggressors learn to associate the presence of these color patterns with the experience of pain and discomfort.  Thereafter, they keep their distance to avoid any trouble.  In return, the potential victims of this unsolicited aggression escape injury and retain their defenses for use against yet-to-be-enlightened pursuers.  Thanks to their threatening appearance, the chances of survival are increased for these would-be victims without the need to risk death or injury while deploying their venomous stingers, poisonous compounds, or other defensive measures.

European Paper Wasp
Armed and Dangerous  The yellow-and-black color pattern on this European Paper Wasp signals a potential aggressor that they have come upon a social insect and could be struck with a venomous sting.  The warning colors alone may be all the defenses necessary for this wasp to survive an otherwise fatal encounter.

One shouldn’t be surprised to learn that over time, as these aforementioned venomous, poisonous, and foul-tasting critters developed their patterns of warning colors, there were numerous harmless animals living within close association with these species that, through the process of natural selection, acquired nearly identical color patterns for their own protection from predators.  This form of defensive impersonation is known as Batesian mimicry.

Let’s take a look at some examples of Batesian mimicry right here in the Lower Susquehanna River Watershed.

Suppose for a moment that you were a fly.  As you might expect, you would have plenty to fear while you spend your day visiting flowers in search of energy-rich nectar—hundreds of hungry birds and other animals want to eat you.

Greenbottle Fly
You might not hurt a fly, but plenty of other creatures will.  This Greenbottle Fly relies upon speed and maneuverability to quickly flee predators.
Common Flesh Fly (Sarcophaga species)
Like the Greenbottle Fly, the Common Flesh Fly (Sarcophaga species) needs to be constantly vigilant and survives by being quick to the wing.

If you were a fly and you were headed out and about to call upon numerous nectar-producing flowers so you could round up some sweet treats, wouldn’t you feel a whole lot safer if you looked like those venomous bees, wasps, and hornets in your neighborhood?  Wouldn’t it be a whole lot more fun to look scary—so scary that would-be aggressors fear that you might sting them if they gave you any trouble?

Suppose Mother Nature and Father Time dressed you up to look like a bee or a wasp instead of a helpless fly?  Then maybe you could go out and collect sweets without always worrying about the bullies and the brutes, just like these flies of the lower Susquehanna  do…

FLOWER FLIES/HOVER FLIES

The Common Drone Fly (Eristalis Tenax) is a Honey Bee mimic
The Common Drone Fly (Eristalis tenax) is an unarmed Honey Bee mimic.  This one is gathering nectar on goldenrod flowers.
Transverse Flower Fly (Eristalis transversa)
The Transverse Flower Fly (Eristalis transversa) is another bee mimic.  Members of the genus Eristalis scavenge carcasses in aquatic habitats.  Their larvae are known as rat-tailed maggots, a name that references their long siphons used for breathing surface air while submerged in ponds, streams, and wetlands.
Spilomyia species Flower Fly
Flower flies of the genus Spilomyia are convincing mimics of temperamental yellowjacket wasps.
Yellowjacket Hover Fly
The Yellowjacket Hover Fly (Milesia virginiensis) is usually heard long before it is seen.  It will often approach people and persist with a loud buzzing, sounding more like a bee than a bee does.  Scary, isn’t it?
 Maize Calligrapher
The Maize Calligrapher (Toxomerus politus) is a hover fly mimic of wasps.  Seen here on Indiangrass, it is believed to associate primarily with Corn (Zea mays).
The Narrow-headed Marsh Fly (Helophilus fasciatus) is a wasp mimic.
The Narrow-headed Marsh Fly (Helophilus fasciatus) is a wasp mimic.  Like other mimics of hymenopterans, they are important pollinators of flowering plants.
Syrphus species Hoverfly
This hover fly of the genus Syrphus is another wasp mimic.

TACHINID FLIES

The Feather-legged Fly (Trichopoda species) is a wasp mimic.
The Feather-legged Fly (Trichopoda species) is a wasp mimic.   Its larvae are parasitoids of stink bugs and leaf-footed bugs.

BEE FLIES

Bee Fly (Exoprosopa species)
Bee flies of the genus Exoprosopa convincingly resemble bumble bees.
Bee Fly (Exoprosopa species)
The larvae of Exoprosopa bee flies are believed to be parasitic on the larvae of the parasites of bee and wasp larvae that mature in the soil.  Confused yet?

So let’s review.  If you’re a poor defenseless fly and you want to get your fair share of sweets without being gobbled up by the beasts, then you’ve got to masquerade like a strongly armed member of a social colony—like a bee, wasp, or hornet.  Now look scary and go get your treats.  HAPPY HALLOWEEN!

Noxious Benefactor

It’s sprayed with herbicides.  It’s mowed and mangled.  It’s ground to shreds with noisy weed-trimmers.  It’s scorned and maligned.  It’s been targeted for elimination by some governments because it’s undesirable and “noxious”.  And it has that four letter word in its name which dooms the fate of any plant that possesses it.   It’s the Common Milkweed, and it’s the center of activity in my garden at this time of year.  Yep, I said milk-WEED.

Now, you need to understand that my garden is small—less than 2,500 square feet.  There is no lawn, and there will be no lawn.  I’ll have nothing to do with the lawn nonsense.  Those of you who know me, know that the lawn, or anything that looks like lawn, and I are through.

Anyway, most of the plants in the garden are native species.  There are trees, numerous shrubs, some water features with aquatic plants, and filling the sunny margins is a mix of native grassland plants including Common Milkweed.  The unusually wet growing season in 2018 has been very kind to these plants.  They are still very green and lush.  And the animals that rely on them are having a banner year.  Have a look…

The flowers of the Common Milkweed were exceptionally fragrant this year.  At their peak in early June, their hyacinth-or lilac-like aroma was so prevalent, it drifted into the house and overwhelmed the stink of the neighbor’s filthy dumpster that he had placed 12 feet away from my walls (100 feet from his).
Common Milkweed attracts a pollinating Greenbottle Fly (Lucilia species).  The dumpster attracts the invasive House Fly (Musca domestica), carrier of dysentery, typhoid, and other wonderful diseases.  Are you following this?  Remember as we proceed, milkweed is noxious.
Busy Eastern Carpenter Bees (Xylocopa virginica) load up with pollen from the flowers of the Common Milkweed.
A Red Milkweed Beetle (Tetraopes tetrophthalmus) munches on a tender fresh Common Milkweed leaf in mid-June.
Following the pollination of the flowers, seed pods will begin to grow.  I trim these off the plants.  The removal of the extra weight allows most of the stems to remain erect through stormy weather.  You’ll still get new plants from underground runners.  As you may have guessed, I’m trying to keep these plants upright and strong to host Monarch butterfly larvae.

I’ve planted a variety of native grassland species to help support the milkweed structurally and to provide a more complete habitat for Monarch butterflies and other native insects.  This year, these plants are exceptionally colorful for late-August due to the abundance of rain.  The warm season grasses shown below are the four primary species found in the American tall-grass prairies and elsewhere.

Big Bluestem, a native warm-season grass in flower.
Little Bluestem (Schizachyrium scoparium “Fort Indiantown Gap”) in flower.  This variety grows on the tank range at the military base where the armored vehicles and prescribed burns substitute for the  herd animals and fires of the prairie to prevent succession and allow it to thrive.
Partridge Pea can tolerate sandy soil and is a host plant for vagrant Cloudless Sulphur butterflies.
Black-eyed Susan (Rudbeckia hirta) is a popular native grassland wildflower.
Indiangrass (Sorghastrum nutans) in flower.  This and the other native plants shown here are available as seed from Ernst Seed Company in Meadville (PA).  They have an unbelievably large selection of indigenous species.  You can plant a small plot or acres and acres using really good mixes blended for purposes ranging from reclaiming pipeline right-of-ways and strip mines to naturalizing backyard gardens.
A Red Admiral (Vanessa atalanta) butterfly, a migratory species like the Monarch, on Purple Coneflower (Echinacea purpurea).  Yes, it is that Echinacea.

There was Monarch activity in the garden today like I’ve never seen before—and it revolved around milkweed and the companion plants.

A female Monarch laying eggs on a Common Milkweed leaf.
A third instar Monarch caterpillar with Oleander Aphids (Aphis nerii) on a Common Milkweed leaf.  Both of these insect species absorb toxins from the milkweed which makes them distasteful to predators.
Fifth instar (left and center) and fourth instar (right) monarch caterpillars devour a Common Milkweed leaf.  There were over thirty of these caterpillars in just a ten by ten feet area this morning.  I hope if you’re keeping a habitat for Monarchs, you’re enjoying the same fortune right now!
A slow-moving Monarch stopped for a break after making the circuit to deposit eggs on milkweed throughout the garden.
Third instar (top), fourth instar (right), and fifth instar (left) Monarch caterpillars quickly consume the leaf of a Common Milkweed plant.  Caterpillars emerging from eggs deposited today may not have sufficient late-season food to complete the larval segment of their life cycle.  Need more milkweed!
After benefitting from the nourishment of the Common Milkweed plant, a fifth instar Monarch caterpillar begins pupation on Big Bluestem grass.
Two hours later, the chrysalis is complete.
Another chrysalis, this one on flowering Switchgrass just two feet away from the previous one.  An adult Monarch will emerge from this pupa to become part of what we hope will be the most populated southbound exodus for the species in over five years.
There it is, soon ready to fly away.  And all courtesy of the noxious milkweed.
A chrysalis can often be found on man-made objects too.  This one is on the rim of a flower pot.
Ornamental flowers can attract adult Monarch butterflies seeking nectar.  I am now more careful to select seeds and plants that have not been treated with neonicotinoid insecticides.  There’s growing concern over the impact these compounds may be having on pollinating species of animals.  Oh…and I don’t mow, whack, cut, mutilate, or spray herbicides on my milkweed  But you probably figured that out already.

 SOURCES

Eaton, Eric R., and Kenn Kaufman.  2007.  Kaufman Field Guide to Insects of North America.  Houghton Mifflin Company.  New York.