To be a bee or not to be a bee? Oh. Mimicry.

A fly takes a sweet drink
A fly takes a sweet drink

A warm mid-October day has invited the flies and the bees to get a last sip of supper from the white daisies that bob their heads in an autumnal zephyr. The six-legged sippers dance and swirl on a yellow stage of the flower disks at the center of the white-petal apron. The tongues and siphon mouths probe each floweret for nectarel treasure. I pull out my camera to sip the nectar of the scene. I focus on a fastidious honeybee who doesn’t mind a close-up, or is too concentrated on tasting each floweret to notice. I watch her letter-opener of a tongue plunge and retract. The large, dark oval of her eyes are set on either side of her fuzzy head of dingy yellow hairs. The wings attached to the fuzzy tennis-ball of her thorax. Her abdomen appropriately the color of light-honey. She hop-flies to another flower.

 

I find another bee.

 

She is turned away from me so I only get a shot of her abdomen and wings. I change my angle. Another shot, but still not her head. A few more shots and she turns to me. My mind tells me something’s not quite right, there is a subtlety of appearance that my mind can’t reconcile. Then with the clarity of focus, I see it. Instead of two eyes set on the side of the head, two eyes cover most of the front head like grossly-oversized aviator glasses. I look at the insect again carefully. The abdomen is darker and wider than the honeybee’s. The thorax is fuzzy, but not as hirsute as the bee’s. I am not looking at a bee. I am looking at a fly wearing a honeybee costume. This is the hoverfly, Eristalis tenax.

 

In a gathering of flies, the hover flies almost always show up in costume. This may startle guests because the hover flies are costumed as bees and wasps.

 

In its history, the hover flies have co-evolved with their hymenopteran kin to mimic the motorcycle sleek vespid form of the wasps or the fuzzy patterns of the bees. The hover fly not only mimics the bees and wasps, it also mimics its behavior to clearly signify its bee-ness. The advantage of this mimicry is that other species conduct themselves around a harmless dipteran as though it was a stinging, noxious hymenopteran. The fly gets the benefit of the protection given to a behavior and a pattern that announces danger, without the energetic investment into poisons and stingers.

 

Had I not taken the time to admire the bobbing beauties of the daisies and their six-legged sojourners, I would have simply assumed all the ‘bee-looking’ insects were indeed bees and been careful to avoid an injection from an agitated nectar forager. My childhood lessons of Ozarkian ecology in Arkansas taught me to avoid danger signs. Many a harmless watersnake, which are not pit vipers but look like cottonmouths, which are venomous pit vipers, did not find itself in my hands because I dared not get close enough to its face to see if it had pits or a cottony mouth of white.

 

Being a harmless animal while looking like a dangerous one is called Batesian mimicry and is thought to protect mimics (in this case the fly) from predators who have learned the danger of attacking the model (in this case, the bee). Danger-bluffing may also confer a competitive advantage in the search for food. Bees and wasps can be aggressive and attack other species, particularly during foraging forays. As a result, less aggressive species are less likely to land on a flower already occupied by a hymenopteran bully, or what it thinks is a hymenopteran bully – such as the hover fly. Thus, a hover fly can dine at the daisy’s dinner table with plenty of elbow room.

 

As I watch the fly use its permanent Halloween costume to trick others so it can delight in floral treats, I am confused further. The honeybee is the European honeybee, Apis millefera, which arrived in the United States with the English colonists in the 1600’s. 400 years is not nearly enough time for an American hover fly to adopt the fashion of a European bee. Later I learn that the hover fly is the European hover fly and introduced to the U.S. in the 1800’s. It was, therefore, in Europe that the hover fly, like an evolutionary little sister who wants to do just as her big sister does, began following the honeybee’s fashion sense. It was to the hover fly’s benefit to arrive after the honeybee because the bee-costume might not have worked. Mimicry is predicated on predator’s learning which color patterns are danger and which are food. Without the stinger of the honeybee first arriving, predators would have gobbled up the bee-looking fly.

 

****

 

I have since learned that I have met this fly before, and it was wearing a more grotesque costume.

 

While sampling for invertebrates in a salt marsh pond in Ipswich a new form caught my eye among the wriggling fish, the water beetles, and the dragonfly larvae which look like flattened, alien grasshoppers. A small, dirty white pill of a maggot with a tail twice as long as its body whiplashed awkwardly at the bottom of the bucket like an anemic sperm. I held it in my hand, fascinated by its strangeness and slightly disgusted by its maggotiness. I had heard the term ‘rat-tailed maggot’ before and what wallowed in my looked both rat-tailed and maggoty. I failed to confirm the identity once I returned to the lab. Had I done so, I would have found that I was holding the larval stage of the hover fly.

Upon reflection, it’s strange to find fly larvae in the marsh ponds, which is not an easy way of life. It’s incredibly briny and low in oxygen. For the hover fly, however, a marsh pond is perfect habitat as they thrive in low-oxygen pools and sewage lagoons regularly. And on occasion, in the anus of bipedal mammals who drink water infected with drone-fly eggs.

The maggot is able to live in fetid habitats because the ‘tail’ is a snorkel that it can periscope above the filth for fresh air. Like the mosquito, the low oxygen of tire water, a sewage lagoon, or a marsh pond is not a problem because it gets oxygen from the air, not the water. This also permits the maggot to take up a rectal residence. The snorkel protrudes not only from its anus, but also of the host.

 

We’ve come a long way from the florid prose of daisies of the beginning of this essay, haven’t we?

 

In its evolution, the hover fly has dabbled in two interesting life strategies. As a larva, use a long snorkel so you can live in habitats that most would not dare to occupy. As an adult, don a mask of venom without investing in such.

 

***

I have returned to the daisies. Today is warm again, hot even at 73 F. The hungry mouths of flies and bees and flies that look like bees lap at the daisies. Today’s warmth mimics that of late summer. But, as with the hover fly, there are clues that signal the autumnal truth. The trees are flashing their oranges and reds and yellows like slow turning stoplights. The daisies reside here at Tendercrop Farm and on every shelf of the outside patio orange pumpkins have blossomed. The calendar tells me that in two weeks many of us will wear a costume and a mask to hide the truth of ourselves for a day.

But, if you’re like me, some last longer than a day.

I consider the masks I wear. The mask of bravado and humor for my sister and brother and mother. One that hides the anxiety and fear. The mask of knowing in a conversation with a colleague or superior to hide my blatant ignorance. The tense smile and ‘It’s okay,’ to hide my utter frustration and irritation with a partner. I costume myself in these lies for the same reason the hover fly wear’s its bee-costume, for protection.

****

Okay, let’s play a game. Which is the bee and which is the fly? If you hover your mouse over each pic it will tell you the answer (look in the bottom left corner of your screen).

Honeybee, Apis millifera, Newbury, Massachusetts (3)

European hover fly, Eristalis tenax, Newbury, Massachusetts  (2)

European hover fly, Eristalis tenax, Newbury, Massachusetts  (1)

Honeybee, Apis millifera, Newbury, Massachusetts (7)

European hover fly, Eristalis tenax, Newbury, Massachusetts  (4)

Honeybee, Apis millifera, Newbury, Massachusetts (1)

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2 thoughts on “To be a bee or not to be a bee? Oh. Mimicry.

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