Cicada emergence: Fiber optics detect noisy insect calls

This proof-of-concept study suggests using optical fiber sensors to monitor and map the populations of these insects. 

“I was surprised and excited to learn how much information about the calls was gathered, despite it being located near a busy section of Middlesex County in New Jersey,” said Jessica Ware, co-author and entomologist, in a press statement. 

Testing of fiber optic cable

In 2021, one of the largest cicada populations, known as Brood X, came out of hibernation in at least 15 states and the District of Columbia, including the Midwest and mid-Atlantic areas of the United States.

NEC Laboratories America, Inc. researchers seized this opportunity to evaluate the functionality of their fiber-sensing test device. The device consisted of a 50-kilometer wire combined with a sensor capable of detecting disturbances with an impressive accuracy of up to one meter.

The wire was erected on three utility poles, each 35 feet tall, on the grounds of NEC's laboratory in Princeton between June 9 and June 24. The goal was to test the system's capacity to identify and analyze the noisy cacophony of Brood X cicadas in the surrounding trees.

The buzzing of the insects was audible, as expected. In fact, the sensor equipment picked up a strong signal at 1.33 kilohertz (kHz). 

Surprisingly, the detected frequency signal matched the cicadas' cry as recorded by a conventional audio sensor placed at the same place.

According to the researchers, technology might open the way for the creation of new types of sensors to monitor insects.

"We think it is really exciting and interesting that this new technology, designed and optimized for other applications and seemingly unrelated to entomology, can support entomological studies," said researcher Sarper Ozharar. 

The findings were reported in the Entomological Society of America’s Journal of Insect Science.