Lucanus cervus (Linnaeus, 1758) is involved in the Near Threatened (NT) danger category in the IUCN Red List. It plays an important role in the ecosystem, nutrient cycling, and the decomposition process of wood. Its larvae live under or in damp and decaying trees. We designed an equipment to ensure the detection and the long-term monitoring of Lucanus cervus and many other insect larvae that complete their larval stages in a wood tissue without destroying their habitats. The equipment developed is an audio listening device that amplifies the larval sounds. This device was designed as a 4-stage structure with a sensor stage, low and high pass filter stage, voltage gain sound amplifier stage, and output stage. This device was used for the first time in the larvae's natural environment. With this new equipment, listening was performed on decaying trunks in the Amanos Mountains, which are included in the spreading area of Lucanus cervus akbesianus Planet, 1896, located within the borders of Hatay province in June-July 2017. The presence of the larvae of Lucanus cervus akbesianus was detected in oak tree trunks, and sound recording was performed. Accordingly, the larvae made approximately 5 clicks in a series and left a 7-8 second gap between two series. It is considered that the audio listening device developed in this study is an effective method for the detection of other saproxylic beetles larvae in decaying wood.