I used to think of houseflies as annoying but relatively harmless pests. Living in the country, we’d often have one or two buzzing around inside the house if we’d left a door open for any length of time (2-3 seconds was usually enough).
Then my opinion changed. I needed to research flies, specifically the genocide thereof, and I learned that they are so far from harmless that they’ve lapped past harmless from the benign side and are again halfway up the scale, double-plus vile, infectious, and all around revolting. The memory of this event makes me shudder. Even after four weeks, my mouth involuntarily pulls into a grimace of disgust at the thought.
OK, here we go. Brace yourself. Bite down on a rubber puck if you have one handy.
We had some friends in to warm up the new house. We put a spread of food on the table inside, and because everyone was sitting outside on the deck, we left the sliding glass door open to facilitate anyone’s inclinations to feed. (Friends don’t let friends drink on an empty stomach. Also, friends don’t let friends walk into screen doors with a glass of red wine in one hand and an expensive wool carpet within splash radius.) The open door was an invitation to more than our guests — the neighborhood flies crashed the party.
This became clear when I watched through the window as someone went inside to get food. As he approached the table, what appeared to be a few dozen flies lifted off and swarmed around. This was disturbing, although in retrospect perhaps not as disturbing as the fact that my friend ate the food anyway. I went inside after him to drape plastic wrap over everything still on the table.
At some point later, it occurred to me to close the sliding door. There seemed to be fewer flies than previously near the table, and for a moment I thought the rest had flown back outside. And then I looked up in horror to see all of them, and their extended families, with guests in from neighboring counties, clinging to the ceiling. There were hundreds.
I couldn’t imagine going after hundreds of flies with a flyswatter, and I definitely didn’t want to scar the ceiling with hundreds of little fly-stains. I tried to suck them up with the vacuum, but was unsuccessful; the flies saw me coming and took off long before the suction reached them. Having no solution, we went to bed that night with a couple hundred houseflies on the living room ceiling. That’s not a restful thought, I can tell you.
The next morning, we purchased and installed flypaper strips. These are an inadequate solution, because flypaper works only work passively — if a fly happens to land on it, he’ll stick, but otherwise the strips are ineffective. (But sometimes a fly will manage to brush up against the edge of the strip while in flight, and catch a wing in the goo. This must be a hard way to go, glued by one’s back and hanging in the air with legs dangling. If flies have nightmares, this must rank near the top. Be sure to add in the visual of a hex-tiled image of the gloating homeowner (armed with a vacuum hose) to complete the effect.)
I researched fly-killing techniques online. My stomach turned, reading about where flies congregate (near garbage, sewage, manure, and the eye secretions of cattle) and the number of diseases they serve as vectors for (typhoid, diarrhea, dysentery, cholera, poliomyelitis, anthrax and tuberculosis). I was particularly disturbed by this description of using “spot cards” to measure infestation level: “Spot cards are 3-inch by 5-inch white index cards attached to fly resting surface… A count of 100 or more fecal or vomit spots per card per week indicates a high level of fly activity and a need for control.” My white ceiling was one big “spot card.”
We quickly developed winning techniques for fly management. I returned to the vacuum, but I altered my technique. Rather than trying to slam the nozzle around the fly, I moved very slowly, sneaking up behind each one at a pace below its threshhold of concern. When I got within three inches, the fly would take off — up and backwards, generally — right into the slipstream. It was gratifying to hear the whack when the flies smashed into the side of the tube on their way to the bag. My new vacuum technique was about 80% effective — best on windows (perhaps the bright light outside masks the “overhead” image of the vacuum approaching), decent on the ceiling, but not so good on the floor.
My wife became a terror with a dishtowel. This approach is superior in kitchens, better even than a flyswatter, because a towel is lethal around uneven surfaces (edges and corners). We’re both about 90% effective with the towel.
The U. of Cambridge’s Insect Vision Group website offers some interesting PDFs that explain about compound eyes and fly vision: Seeing the brain through a fly’s eye.