How exactly are they measuring air temperature?
It is midsummer and water striders have gathered in this irrigation ditch prior to entering dormancy. Once the summer solstice passes the days slowly start to shorten. This group formation and summer dormancy begins when the day is about 1 hour shorter than when the water striders hatched. When the temperature drops below 25 degrees Celsius they awake from their dormant state and commence breeding. [6’22″/Subtitles: English]