Hartley Magazine

All the latest news, hints, tips and advice from our experts

Foolproof Fly Control – Part 6

If there is one thing I absolutely hate about my greenhouse in the summer, it is the buzzing flies that accumulate in the apex of the roof in hot weather.

I hate the noise that they make; that incessant buzzing sound as they flit around above my head and interrupt my silent thoughts. I hate to think of them landing on my lovely tomatoes, or resting on the cucumbers that I will slice into my salads. I hate the thought of their dirty feet walking over my salads. I hate flies. I know they have a role to play in the bigger picture and the food chain and yet I find them distinctly grotesque.

If flies bug you too and you want to use a brilliant and foolproof method to get rid of them from your conservatory and glasshouse then read on. You don’t have to touch them, you don’t have to deal with dead bodies and it works.

It’s a brilliant way to get the kids interested in plants; use carnivorous plants. As a youngster I saved up my pocket money for weeks to buy a Venus fly trap. There never seemed to be any flies caught by my plant and I worried that it would starve, so one day I fed it corned beef. It died. Who knows why it died, more likely it was because I didn’t use rainwater to water it and it died of chlorine poisoning, but maybe the corned beef played a part too. Whatever it was I was fascinated, though I have to admit I never bought another Venus flytrap.

Since then I have discovered a much more reliable fly eating plant. The pitcher plant Sarracenia is particularly easy to grow, ideally suited to growing in a glasshouse or conservatory and extremely efficient at eating flies. Carnivorous plants fool their prey with cunning disguise, mimicking delectable scents and tastes until the unsuspecting bug falls to it’s death into a sea of rotting corpses, or is captured in the teeth of snapping jaws. It’s gruesome at best, but these plants have evolved to tackle the problem by calm, rather than by storm, ultimately benefiting from the high nutrient content of the pests that they devour – the freshest kind of fertiliser.

It’s nature performing at her best. Each plant species has evolved so that its life cycle runs parallel to its prey. By summer, it is the larger and later developing North American pitcher plants (Sarracenia) that are actively catching wasps and flies. Once lured into the elegant green tubes there’s no escape as the insect rattles and buzzes around in a tiny padded cell. It’s an untimely death, benefiting only the predator that will feed off its vital juices. What’s more just one established plant will keep the greenhouse or conservatory clear of flies all summer.

Expeling some myths

Insect eating plants do not smell. Although the insects do rot down, the greenhouse and conservatory is not filled with the stench of rotting meat.

The plants are not poisonous and are safe for children and pets. In fact it is the plants that are more at risk from over inquisitive fingers poking and prodding to get them to do their stuff. Nevertheless they provide a fascinating albeit macabre way to get children interested in plants


The main rule with growing pitcher plants is to ensure, without fail, to keep them well watered with rainwater. Never use tap water, it will kill them. .

You don’t have to empty the traps, once they are full; the contents rot down and are absorbed into the plant as vital nutrients for growth.

Most carnivorous plants need acidic growing conditions and lime free water. Fill a suitable container with about 2cm of rainwater and place the plants in this.

Don’t put carnivorous plants in a greenhouse environment where you are actively (recently) using biological control, as they will catch the predators too. Instead place them outside the greenhouse where they should catch the beasts before they gatecrash your space.

Carnivorous plants shouldn’t need additional fertiliser. If you are concerned that they aren’t catching enough flies, place them outside for a few days.