August the cruellest month for bugs

It has been a miserable summer for bugs as well as people, the head of Britain's insect conservation charity has said.

Although the plight of butterflies in summer 2008 has been publicised, other insect groups have suffered severely because of the weather, explained Matt Shardlow, director of Buglife, the invertebrate conservation trust.

Dragonflies, hoverflies, aphids, ladybirds, bumblebees, solitary bees, moths and mayflies have all been in short supply in gardens and in the countryside in recent weeks. "It's been a dismal summer for bugs," Mr Shardlow said. "Sun-loving bugs have been particularly hard hit by the clouds and rain. We're very concerned that numbers have been so low. This also means that there is less food for the birds, and fewer flowers being pollinated."

The combined effect of low temperatures and rain has presented Britain's invertebrates with a double whammy. As insects are cold-blooded they need the warmth of the sun to raise their body temperatures in the morning and allow their muscles to work. A cool day means this cannot happen and they are unable to forage for food, such as nectar from flowers and plants, or other smaller insects as prey – and a succession of such days can be fatal.

Extended periods of rain not only lower temperatures but can wash away insects such as aphids and similarly affect the eggs and caterpillars of butterflies.

Hoverflies, the harmless wasp lookalikes, do gardeners a favour by consuming masses of aphids – but this year they have been much less common, perhaps because aphids are scarcer. "There are very few around," said Mr Shardlow. "Their numbers picked up in July but they have just slipped back down again."

Ladybirds, which also feed on aphids, are also few and far between. One of the insect traps of the Rothamsted agricultural research centre in Harpenden, Hertfordshire, contained 283 sycamore aphids in late August – compared with 5,290 at the same time last year.

Bumblebees and solitary bees continue the story, not least because they are particularly affected by the cold. "They need warmth to get going," Mr Shardlow said. "There have been very few around in August."

Dragonflies present a similar case, says Mr Shardlow: "They have been doing OK as larvae because they have an aquatic stage but when they come out, they are not getting the amount of sunshine big dragonflies need to get kick-started and start their predation. Also without the same number of flies, there's not as much food and that will result in shorter life spans."

No relief is in sight. Torrential rain and high winds will sweep across much of Britain today, tonight and tomorrow. Severe weather warnings have been issued for south-west England and Wales for this morning, and for north-eastern England for later today and tonight. As much as 50mm of rain may fall during the day – a fortnight's amount. "This is being caused by a deep depression, the first of the autumn," a Met Office spokesman said.

Aphids missing

283

Number of sycamore aphids caught in trap at Rothamsted agricultural research station in Hertfordshire in 2008

5,290

Number caught in the same trap last year

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