LONDON — To gauge the health of the environment, look to the butterfly.

The delicate, colorful insects that help to pollinate many an English garden may not live very long (the monarch butterfly has a life span of two to six weeks), but knowing how well their colonies are faring and how many are flitting around can be crucial indicators of a calamitous or a thriving environment.

That’s where the Big Butterfly Count in Britain comes in.

The call has gone out for legions of volunteers to join the campaign, which runs from Friday to Aug. 12, and submit their sightings of butterflies and day-flying moths.

The effort, called the world’s biggest butterfly survey, has the backing of the British broadcaster and naturalist David Attenborough, who is also the president of Butterfly Conservation, the charity that organizes the effort. Mr. Attenborough told the BBC that watching butterflies in his garden takes his mind off “the woes of Brexit,” referring to Britain’s contentious exit from the European Union.

The survey began in 2010, and last year, a record 60,000 people turned in 62,500 counts of butterflies and day-flying moths from across the United Kingdom, according to Butterfly Conservation, which describes the effort as the largest butterfly count in the world.