The Devil You Know

Summer.  Could there be a lovelier time of year?  The sun is bright, the lakes are warm, and the days are long and lazy.  I like to spend such days basking on the back porch, a book in one hand, a hamburger in the other.  Once, after setting my burger down on its plate to turn the page of my book, I noticed a little black insect crawling on my whole-wheat sesame seed bun. On closer inspection, it revealed itself to be the musca domestica, better known as the housefly.  I studied the insect closely, my nose mere centimetres away from its translucent wings.  I like to think that its leg-rubbing was a friendly hello.

Since ancient times, flies have been thought of as a symbol of plague, and rightly so. Typhoid, cholera, dysentery… these are just a few of the parting gifts our household pests can spread before we swat (or zap) them into oblivion.  Perhaps the ancient Christians were right in naming the Devil the “Lord of Flies.” For while he spread sin and fed on the souls of the wicked, flies spread germs and gorge on our refuse.  Between their talent of crawling over every inch of our homes and their squalid eating habits, houseflies make up an ideal taxi service for germs.

A fly’s foot, known as a tarsus, is an amazing thing.  Hook-shaped claws allow him to grip rough surfaces, such as cloth and plaster.  To walk across something smooth like a window pane, however, he has another device.  This is the tarsal pad, which oozes out a sticky substance, perfect for that temporary hold.  The tarsus has one other trick, perhaps the most baffling of all.  Not only is it a foot for walking, it is a foot for tasting.  Sensory organs, taste-buds if you will, are also located in the tarsal pad. It’s no wonder fly-fashion forbids the wearing of shoes.

One man’s trash is a fly’s main course; food scraps, forgotten relics of dog walks, and general filth are all a gourmet buffet of the finest delicacies.  Of course, flies have always been lazy brutes, and so have yet to evolve a sense of decency.  Instead of sitting politely by and demurely waiting for the next course, a fly will scuttle all over the dinner table (in this case, the trash bin), tasting with his feet until he finds something to his fancy.  As he moves through rubbish, bacteria, viruses, and parasites cling to the hairs on his legs, thorax, and wings, as well as his sticky tarsal pads.   It’s a beautiful relationship; the fly gets a half-rotted, perhaps partly fermented meal, and the germs get a free ride to their next destination: our plates.

Now, looking back on that hot summer day when I watched the fly take a tour of my burger, my stomach takes a nasty turn.  Not only was he leaving a map of fecal-footprints, but potentially a big X as well.  Perhaps the leg-rubbing wasn’t a bon jour at all.  Perhaps it was more akin to the hand-wringing of a cartoonish villain.  I fear for the worst, but perhaps… perhaps I witnessed a fly taking a dump.  Fly pie.  With a side of Ebola*, courtesy Flermy Taxi Service.  Smack in the middle of my whole-wheat bun.

While flies spread some of the deadliest germs known to man, we humans have developed- over hundreds, if not thousands of years- a partial immunity to most of them.  Our ancient ancestors, living in their hovels with their pigs and goats, were subjected to far more germs than we are, and not only because their were more flies buzzing around.  No, humans used to be just as filthy.  And yes, I mean that in the fecal-footprint kind of way, though perhaps in more of a hand-print sense.  Nonetheless, this has allowed the human race to come out the victor.  So unless you live in squalor with your livestock, no running water, and nothing to use for toilet paper, you shouldn’t fear a visit from Dear Dysentery and Friends.

DiseaseAndHouseFlies_LauraUlrich

*While Muscoid flies could be contributing to the spread of Ebola in rural areas, they likely have little influence in settings where used bandages are properly (and thoroughly) disposed of.

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