The other day I fished a fly out of my Chardonnay. In its struggle, it must have absorbed some of my wine. Sitting on my finger, it cleaned itself carefully and I expected it to fly off somewhat erratically. It flew, however, straight and true for as far as I could see it. So does alcohol not affect insects in the same way as it affects mammals?
鈥� Alcohol affects most animals similarly, including insects, although their sensitivity varies greatly. The answer lies with how our mammalian morphology differs from that of typical insects.
Mammals have a distinctly perverse arrangement of breathing and swallowing mechanisms. Whenever we swallow, our survival rests on a complicated arrangement of sensors, reflexes and valves that marshal the traffic so that we may eat, drink, breathe and be merry, with only the occasional life-threatening slug going down the wrong way.
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A fly鈥檚 respiratory system, on the other hand, has its own complications, but it inhales only through spiracles that are totally separate from the alimentary tract. So when struggling for survival in wine, none of its reflexes cause it to swallow.
Many non-aquatic insects can survive for hours in fluids that would drown a human in minutes. Your fly may have swallowed a sip while grooming, but would not have gulped enough to affect its ability to stay on a chalk line.
Jon Richfield, Somerset West, South Africa
鈥� The natural inclination for a flying insect is to fly in an erratic path. This helps it to avoid being eaten by a bird. However, when it is drunk it has trouble doing this and tends to fly in a straight line.
To test if the insect has had too much to drink, put it on a piece of paper and draw a straight line out from its nose. If it can follow the line without wavering, it is drunk and should not be permitted to fly for its own safety.
鈥淭he natural inclination for an insect is to fly an erratic path. This helps it to avoid being eaten by a bird鈥�
Hugh Roberts, Nelson, New Zealand
鈥� In the 1950s, while I was living in the tropics, an emerald green grasshopper flew into the ceiling fan and landed, stunned, next to my father鈥檚 beer glass. My dad carefully put a few drops of beer into a bottle cap and balanced the grasshopper on the rim. It had a drink, staggered around and finally flew away.
Amazingly, the grasshoppper came back the following two nights and enjoyed a tipple with my dad. Sadly, on the third night it died, unnoticed, in his beer glass.
I would be happy to receive verification from your readers that grasshoppers might enjoy alcohol because this story is usually met with disbelief and derision.
Whether flies have similar tastes to us and to each other is a mystery to me, however.
Sue Macpherson, By email, no address supplied
鈥� Some insects do react to alcohol, or at least seem to. About 50 years ago I was in a village pub in Kent with some friends and we spilled beer on the table. A large moth landed and began sucking up the beer. When it had finished, it described an ever-wider spiral on the table-top and fell off on to the floor. This may not be conclusive evidence, but it gave a very convincing impression of being extremely drunk.
Ian Stewart, University of Warwick, Coventry, West Midlands, UK
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This article appeared in print under the headline 鈥淔ly fishing (hic)鈥�