It’s one of Britain’s most beloved insects, the subject of children’s rhymes and a friend to gardeners.

But ladybird numbers are down by more than half in some parts of the country this year as a cold, wet spring flattens their numbers, naturalists say.

Gardeners have been urged to record beetle sightings and create habitats for the insects to help them recover from the poor start to the year.

A burst of warm weather early in the year brought adult ladybirds out of hibernation, with many then struggling to survive amid unseasonably cold and wet weather in April and May, which also affected their major food source, aphids.

Ben Keywood, entomologist at Sheffield and Rotherham Wildlife Trust, said he had observed numbers of key ladybird species 60 per cent lower than in previous years.

"I’ve been recording insects for a couple of decades now. I’ve never seen such a steep decline in populations at this time of the year," he said.

"Some years we’ve already had a second generation of ladybirds that have come out.

"If it’s a warm spring, the ones that overwintered will lay their eggs in March, their larvae will feed through April or May and by now we could be having a second generation of ladybirds already appearing.

"So far this year I haven’t seen a ladybird larva, so things are definitely behind. I don’t remember another year like this."

Britain has over 40 species of resident ladybird, including the native two-spot, seven-spot and 11-spot.

Since 2004 the invasive Harlequin ladybird, originally from Asia, has also been in the UK, outcompeting native species for food and eating their larvae and eggs.

This is thought to be behind the decline in native species, with a report published in 2015 by the UK Ladybird Survey concluding that seven out of eight native species of ladybird were declining, a pattern linked to the arrival of the harlequin.

Professor Helen Roy, who co-leads the survey, said she was hopeful that overall ladybird numbers would recover this year as the weather improves.

"Insects can catch up very quickly. If we now have some good weather and lots of aphids, the ladybirds will all very rapidly go through their life cycle and catch up from where they are at the moment," she said. 

"We certainly saw good numbers of seven-spots emerging from their winter habitat, and we’ve got lots of records coming in.

"I would absolutely agree that I’m not yet seeing the larvae or the pupae but we are seeing the ladybirds mating.

"They are about and they are getting going and they have every possibility of catching up."

Scientists at the agricultural institute Rothamsted Research track aphid numbers to help farmers and horticulturalists understand the threat level from the pest, which can damage crops.

Dion Garrett, a PhD student at the institute, said aphid numbers had increased rapidly over the past few weeks.

"You get that lag effect when you start seeing an influx of pests or prey, and you then start seeing the predators and the parasites picking up a few weeks after that," he said. 

"I would have thought within a couple of weeks we’ll start seeing a lot of ladybird larvae eating on the influx of aphids."

Professor Brian Eversham, entomologist and chief executive of Bedfordshire, Cambridgeshire and Northamptonshire Wildlife Trust, said: "The amount of rain we had in May will certainly have affected a variety of insects – including beetles.

"Because flower-visiting beetles don’t generally feed on deep ‘bee’ flowers – where nectar is sheltered by the tubular flower structure – their favoured plants, such daisies and hogweed, are prone to being literally washed out by rain.

"By recording what’s found in your garden – and creating more diverse habitats – gardeners can play a central role in helping to understand how beetles and other insects are doing this year."