A recent spell of warm weather has brought about an explosion of plant pests.

Along with scale insects, thrips, whitefly and others, aphids are sap-sucking pests. They are rarely responsible for directly killing plants but they can weaken them and spread viruses.

Ornamental plants can be rendered extremely unsightly, especially when all the conditions are right for a spate of exponential growth in pests.

Horticultural lecturer and author of The Plant Listener, Julie Kilpatrick, says she has recently received a lot of questions from plant owners who are horrified at the numbers of black, green or brown insects infesting their plants. She is urging gardeners not to reach for the sprays

She said: "Yes, the aphid numbers are rising but this means food for ladybirds and other beneficial insects and their populations are rising as a result.

"This is a natural phenomenon – pests increase in numbers but, following closely behind are the predators until, eventually, you reach a point where, all things being equal, the populations settle back down again.

"I’ve seen a lot of ladybirds mating recently and this means they’re responding to the availability of food.”

One female ladybird can lay up to 1000 eggs in a season and ladybird larvae are ferocious consumers of aphids and other sap-sucking pests.

However, the larvae are quite small and they look like tiny little crocodiles so many gardeners don’t recognize them as friendly visitors. As a result, they often fall victim to insecticides. Insecticide sprays, including many of those labelled organic, kill most beneficial insects too and ladybird larvae are especially vulnerable.

Julie said: “I totally understand the need to apply insecticides in some situations, especially if your livelihood depends on it but I believe ordinary gardeners like me should be prepared to take a few losses for the sake of the bigger picture.

"If we have a little patience and don’t resort to chemicals, a short spell of cold weather should knock down the numbers of pests and all that ladybird sex I’ve been witnessing, will result in eggs hatching pretty soon. So don’t panic, the ladybirds have got it covered and, this year, I’ve a feeling we’ll be seeing a lot more ladybirds than we’re used to.”