More than 25,000 people across the UK took part in the Big Butterfly Count 2012, counting over 223,000 butterflies and day-flying moths.
Over 1000 took part in Scotland, up from 900 last year, despite the poor weather which saw the country suffer its seventh wettest summer since 1910.
UK-wide, the study of the butterflies and day-flying moths found the populations of 15 of the 21 species had fallen. Eleven common butterfly types had decreased by more than one-third compared with2011.
Butterfly Conservation said the heavy rainfall was putting many already threatened species at risk.
Richard Fox, the charity's surveys manager, said: "The summer of 2012 will be remembered for its awful weather and many of our beautiful butterflies have suffered the full force of torrential rain, strong winds and low temperatures. We're on track for one of the worst years on record for UK butterflies. Gardens were bereft of butterflies for much of the summer."
Cold and wet weather increases the mortality of caterpillars and limits the ability of adult butterflies to find mates and lay eggs.
Most species recorded year-on-year decreases, with the number of Common Blue butterflies down by 50% and the Red Admiral, which was abundant last summer, falling sharply; its numbers were down by 72%.