Scientists involved in a conservation project have been bugging the homes of stag beetle larvae.
Tiny microphones are being used to eavesdrop on the white grubs which live in buried rotting wood.
The larvae make rasping sounds known as "stridulation" which experts believe are used as a form of communication.
Listening to the larvae is one new technique being tried out to get a better idea of stag beetle numbers.
The stag beetle, Lucanus cervus, can reach a length of several centimetres. Well known for the dramatic "antlers" sported by males, it was once common but is now classified as "nationally scarce" in the UK.
Stag beetles are still found in southern England but are rare or extinct in the Midlands and North.
Attempts to conserve the insect have been hampered by the lack of reliable population monitoring.
Scientists are also experimenting with ginger to lure flying beetles into aerial traps so they can be counted.
They discovered that adult stag beetles find ginger irresistible. It contains large amounts of alpha copaene, a chemical known to attract insects that live in dead and decaying wood.
The research, published in the journal Insect Conservation and Diversity, was funded by the British Ecological Society, the Forestry Commission, the People's Trust for Endangered Species, and the Suffolk Naturalists' Society.