IT WAS the hottest English summer recorded in 350 years and saw standpipes in the streets and householders told to save water by not running baths or flushing the toilet.
But the heatwave and drought of 1976 was even worse for insects, researchers in York said today.
The weather sent billions of seven-spot ladybirds swarming in search of food, and had the most devastating effect on butterflies and moths in the 50 years since records began, a study found.
The temperature hit 32 degrees for 15 consecutive days across much of southern England that summer, and some regions had no rain for 45 days.
Since then, the UK has warmed by a full degree Celsius and experienced repeated bouts of extreme weather, from flooding to drought, heatwaves to freeze-ups - but no single year has caused so many butterfly and moth species to crash simultaneously, researchers at the University of York said.
“It was the culmination of a two-year event,” said Dr Phil Platts, co-author of the study.
“Hot and dry conditions stretched back to the spring of 1975. This was initially good for butterflies and moths, and their numbers boomed.
“But then extreme heat and sustained drought in the summer of 1976 tipped the balance, causing numbers to plummet across at least 50 different species.”
The study also looked at the impact of extreme weather on birds, and found that the cold winter of 1981-82 had the biggest effect on their numbers. A third of bird species declined steeply as temperatures fell to minus 26 deg.
The researchers concluded that for many species, extreme weather events had failed to have a lasting impact on population trends.
But global warming is forecast to increase the frequency of such events, and the study says it is likely that some will trigger even greater population changes.
This April was the warmest on record in the UK, and the second warmest globally, beaten only by April last year.
Prof Chris Thomas, of York’s biology department, said: “If we want to avoid a future super-heated drought that will put 1976 in the shade, then we need to address the root cause of climate warming – greenhouse gas emissions.”
He added: “Continued warming will gradually increase the chances that events as severe as 1976 will take place over the coming century.”
However, Dr Platts said cold extremes would become increasingly rare. “Species may be released from historical constraints, such as extreme cold, just as they may be hampered by the new extremes,” he said.