What would Malta (and Gozo) be like without a few friendly flies, right? Wrong. The flies we nonchalantly whisk away from our face and food are teeming with disease-carrying organisms that can make us seriously ill.
Flies need to vomit on our food to be able to eat it
Anywhere that food is prepared – be it household kitchens, restaurants, food preparation, packing or storage facilities – are at risk of contamination.
Flies damage foodstuffs and can make you or your patrons seriously ill. For entrepreneurs in the food industry, the repercussions to public health can come at a very high price, and the resulting damage to their business reputation can be irreparable.
Flies fall into two categories, small and large, and in Malta we have both types. Common small flies include fruit flies and drain flies. Fruit flies are the tiny flies we see hovering around fermenting fruit, wine, fruit juice, or vegetation. Drain flies are the fluffy black flies that live in and around water-drain openings.
Although they are a nuisance, small flies such as these are not generally associated with significant health hazards. But the same cannot be said for their larger cousins.
The most invasive large flies found in Malta are the house fly (Musca domestica), and the blue bottle fly (Calliphora vomitoria). Adult house flies are about six to eight millimetres long, dark grey in colou, with a yellow or copper abdomen, and four dark stripes down the back. Adult blue bottles grow to about six to 12mm long and are usually metallic blue or green in colour, with a hairy body and legs.
These flies are commonly referred to as ‘filth flies’ (dubbiena tal-ħmieġ) because of their disgusting habits. They like to lay their eggs in human or pet excrement, animal manure, decomposing food waste, and the moist decomposing flesh of dead birds, rodents, animals and corpses.
This partiality to putrefaction means they usually live in urban or farming areas where they have ready access to their preferred breeding grounds. Their choice of environment means they pick up a frightening collection of disease-carrying organisms on their legs and body.
That’s all well and good for the flies. But the problem for us is that they also love human food. Foods that flies particularly love include meat, ham, salami, cheese and fish.
Filth flies that settle on our food would almost certainly have first set down on faecal or putrefying matter and so transmit disease directly from their body to our food. As if that isn’t sufficient danger to our health, flies need to vomit on our food to be able to eat it.
Flies cannot chew or bite. Their mouth is designed like a sponge through which they suck up their nutrition. To be able to do this, they liquefy our food by regurgitating onto it and then sucking up the soupy by-product. Fly vomit contains an additional concoction of disease-borne organisms.
A female blue bottle will lay her eggs where she feeds… in our food. She will choose either to deposit maggots that have already grown from eggs inside her abdomen, or else she will lay her babies as eggs and let them mature on our food. Within 18 hours, these eggs will become maggots. Accidentally ingesting food that has been contaminated by a fly can make you seriously ill.
A single fly can transmit over one million viral and bacterial organisms, including salmonella, E. coli, dysentery, typhoid, tuberculosis, intestinal worms, gastroenteritis, anthrax and sometimes even cholera.
Babies and infants are vulnerable not only to these diseases, but also to eye infections when flies settle around their eyes to sup on the vitreous liquid.
Greatest care needs to be taken during the summer months when flies are at their peak. In fact, filth flies reproduce very quickly in warm weather, and the only way to keep them under control is to limit the places where they can breed and feed (see box below).
But sometimes, even the best care in the world cannot prevent a fly infestation from happening.
Flies reproduce prodigiously and a single mated female will lay several batches of 100 to 150 eggs. Barring ill-health, it’s easy to recognise the signs that you have a plague of flies. Clear indicators are ‘fly specks’, the excrement of flies.
Large numbers of blue bottles are a strong indicator of a dead animal in your house, such as a rat. Another indicator is finding clusters of dead flies, or living flies that you cannot get rid of.
Ideally, you should target flies while they are still at the egg (larval) stage. Household remedies such as fly or pesticide sprays may be effective for exterminating adult flies, but they do nothing to redress the larval problem, and within hours your fly infestation may be as bad as ever. Unfortunately, flies quickly become resistant to chemical sprays and successive generations need ever stronger formulations to keep them under control.
Safer options such as fly paper are easily available, but who wants to live with ribbons of dead flies suspended from the ceiling? The fly swatter remains ever useful, but don’t use it anywhere near food or kitchen surfaces because you might actually splat fly blood and body parts all over your dinner.
You might like to try fly traps, but you need to keep them well away from the house or workplace because of their foul odour.
Fans are excellent at creating sufficient air circulation that keeps flies away within a small area. For walk-in businesses, an air curtain can be a useful, albeit very noisy, solution. Alternatively, an insect light trap that is kept out of sight of your patrons is always a good idea.
But for a complete solution to your fly infestation, your best bet is to bring in the professionals.
A professional pest control company is able to accurately identify the various species of fly, locate their source, recommend the appropriate fly control measures, as well as offer advice on how to prevent fly infestations from recurring.
Your specialist pest controller is equipped to clear areas from both small and very large fly problems, as well as multiple species of flies. And they know how to achieve this while observing rigorous standards of safety for your family and pets.
What you can do
• Install insect screens around the kitchen. Check screens regularly for holes or tears, and repair them immediately.
• Always cover food and clear away leftovers immediately. Wipe down appliances from food debris and cooking grease.
• Make sure your garbage bins have tightly sealing lids and take your rubbish out frequently. Regularly wash down your bins with soapy water to remove any residue.
• Clean up after your pets. Flies are likely to settle on their excrement before they land on your food and walk all over it.
• Keep your compost in a compost bin and always covered. Regularly turn over the compost, and don’t put in any fish or animal products or by-products.
• At dusk, close your windows and doors, or draw the curtains to block out the light.
whats.bugging.u@gmail.com
Mario Borg is general manager of a local pest control company.