Glen Rains, an engineer with the University of Georgia College of Agricultural and Environmental Sciences, has developed a novel sensor that uses live trained wasps to detect a particular scent.

The so-called ‘Wasp Hound’ is a 3-inch PVC pipe about 10 inches long. At one end of the device is a fan and a Web camera. The other end sports a tray containing four or five trained wasps and a removable white cap with a tiny pinhole in it.

In use, the fan sucks air through the pinhole in the cap. And if the scent the wasps have been trained to recognise travels through the hole, they crowd around the pinhole. If the scent is not there, they do not.

Through a USB connection, the Web camera sends an image of the wasps to a computer. There, software analyses the amount of dark space created around the pinhole by the wasps against the white background of the cap.

The software then creates a graph that shows the level of crowding, a representation of the wasps' response to the odour they were trained to detect.

"In about 30 seconds, we can know if the wasps picked up anything," Rains said.

The premise of the Wasp Hound is based on the work of Joe Lewis, a US Department of Agriculture entomologist. Over the past two decades, Lewis has learned that parasitic wasps can smell nearly anything and can be taught to respond to smell.

Rains and Lewis use wasps that have been bred in a lab. And through conditioning them to link a certain smell to food, they become little bloodhounds.

Rains has already used trained wasps to detect aflatoxin, a poison produced by fungi that attack crops like peanuts and corn in fields and in storage.

The work that went into the Wasp Hound was funded by the USDA, UGA and the US Department of Defense.