At this link, one may find explained a way of telling the temperature using crickets, an idea most people first encountered on the sitcom Big Bang Theory. It involves careful observation and is based on a number of interesting biological phenomena. Yet it has a weakness, in that it relies on counting the cricket's chirps -- one of that annoying insect's most annoying features. So I propose a method which will be almost as accurate but much quieter:
1) Look at a thermometer.
2) Kill the damn cricket.