A sticky issue as humming houseflies continue to soar

‘God in His wisdom

OGDEN NASH was an American poet with a gift for making a telling point in the minimum number of words. I remembered this one the other day because our house has been invaded by houseflies.

Later that day, I was in the post office and the Post Mistress was complaining about them and then, when my wife went to the hairdressers, it was the same thing.

So I got curious and started to enquire from other friends and neighbours.

I don’t know whether this is a local phenomenon or whether it’s happening nationwide but over the past couple of weeks there has certainly been a plague of houseflies in the part of the country where I live. I don’t know what has caused it but I suspect it has something to do with the weather.

We had a cool, wet summer followed by some lovely weather in September. The life-cycle of the housefly is controlled by temperature. A female fly lays between 100 and 150 eggs at a time, repeating this at intervals. The eggs hatch into larvae which eventually pupate and then turn into winged flies.

This process normally takes place during the summer months in rotting organic matter or garbage. This environment often has a microclimate because the composting or fermenting process creates heat.

The whole process from egg-laying to the appearance of winged flies can take as little as 20 days if it takes place in an environment of 30 degrees. But if the temperature is half of this it can take three to four times as long.

The larvae go through three stages of growth and are conical, whitish creatures that are usually called maggots. Maggots are an important angler’s bait (perhaps this is what God forgot to tell us). The ones most commonly used are the larvae of blowflies such as the bluebottle but housefly maggots are also used for smaller fish.

Anglers and fishing tackle dealers have a vested interest in keeping maggots in their larval form for as long as possible: they cost money and they’re not much good as bait when they pupate and completely useless when they turn into flies. So to prolong their useful life they keep them in the fridge.

My theory is that the bad summer acted like a fridge and the sunny weather in September caused several generations of housefly larvae to mature at the same time. To find out what dangers this might pose I consulted an excellent book: Irish Indoor Insects, by James P O’Connor and Patrick Ashe.

If you’re having your breakfast you may want to skip this quotation from it because it’s quite revolting.

“The adults frequently cause disease in Ireland, especially because of poor hygiene. They feed by first vomiting over their food. Enzymes then break it down and the resultant liquid or broth is sucked up. At the same time, excrement is voided. Although the vomit may transmit disease, excrement is the main source of contamination, as it contains bacteria such as Salmonella.”

So the next question is how to get rid of them. I don’t like using insecticides. I know the ecological damage they have done to the planet in my lifetime. And when other family members smuggled in a can it was covered in safety warnings and turned out to be rather ineffective.

My dislike of those electronic fly killers of the type you see in butcher’s shops is based not on knowledge but on ignorance. I don’t trust them because I don’t know how they work. So now I’m looking for a source of those old-fashioned sticky fly-papers you hang from the ceiling.

* Irish Indoor Insects was published by Town House in 2000 but is now out of print. It may be available second hand or from a library.

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