If your garden is healthy, it should contain 100 or so different insects; there will be many gardens with more and sadly many with fewer.
Out of this 100, about 10 are considered major pests. The RHS publishes a top 10 list of pests based on inquiries to its entomology department. It’s an interesting list, because it varies from year to year and shows some of the vagaries of our changing climate. Glasshouse thrips are learning to exploit the urban island effect, living outside in warm, sheltered city gardens; vine weevils love our containerised city gardens; and the rosemary beetle has learned there is life north of the M25.
From the current list, snails, slugs and aphids are the only ones I regularly find in my garden. Aphids I leave entirely to nature; where there are aphids, hoverflies, lacewings and ladybirds follow. The first lesson of living with pests is, just because it looks gross doesn’t mean it should be squished; you may find you’ve inadvertently dispatched the young of useful pest-munching predators. Pests are a problem only when there are too many of them: a single sap-sucking shield bug is not an issue. If you think something is a problem, pick it off and leave it for the birds. If a plant becomes truly infested, particularly if it’s an annual, bury it deep in your compost – it’s mostly likely toast anyway. It was weak, which is why it became infested. (If you must persist and all else fails, a strong jet of water will dislodge most things.)
The second rule is that standing on slugs, squishing aphids and popping lily beetles is OK as long as you play fair. Chemical warfare makes for a very uneven game. Snails are prettier than slugs, easier to squish and favoured by the sort of garden birds we love. Slugs are tiresome and revolting, but curious and, dare I say it, clever.
The next rule is open to a lot of interpretation, but if it moves very slowly, it’s probably a pest. If something moves fast (and by that I mean faster than a slug), it may well be a predator on the hunt. Learn to recognise the hunters from the hunted. Be a good predator yourself and study your prey. The Opal website has some very good guides to garden invertebrates. Then use the RHS website to find out whether or not it’s a common pest.
And the final rule is this: you have not won if there are no pests left; you’ve lost, because you have destroyed your ecosystem. As naturalist John Muir wrote, “When we try to pick out anything by itself, we find it hitched to everything else in the universe.” Your pests are someone else’s dinner, and in turn so are they. Remove them all and you no longer have an ecosystem – which, ultimately, is what a garden is.
