Sweep Net in the Sky: Team Designs Drone for Insect Scouting

By Ed Ricciuti

The time-honored cartoon caricature that pokes fun at entomologists afield—bespectacled, waving a long-handed sweep net—may have seen its day. Like so many other tasks performed by humans, collecting live insects in the field could soon be replaced by a drone.

An exaggeration, perhaps, but drones have shown they can perform the arduous job of sampling insects in agricultural fields. At least, that is what a paper published this month in the Journal of Insect Science explains. It describes how to build and operate a low-cost drone named “iDrone Bee” that can drag a sweep net through an agricultural field to catch live insect pests so managers can determine the best way to deal with them, if necessary. The University of Idaho scientists who authored the paper predict that drones like the one they describe could “benefit the integrated pest management (IPM) community by minimizing time and efforts” of human workers in the field.

The study comes on the heels of others indicating that drones are feasible for monitoring pest populations. These studies were done with commercially available drones, a fact that could cause a glitch in their real-world use. Foreign manufacturers, often based in China, make most drones sold in the United States, and various federal actions have been taken against some of these companies and their products for security reasons. Two years ago, for example, the U.S. Department of the Interior banned its staff from using Chinese-made drones. In contrast, the iDrone Bee is home-made from open-sourced plans and, what’s more, can be built of motors, controls and other items available from big-box outlets, online retailers, and even some local hardware stores.

Drones for some time have been flown over agricultural fields for a number of purposes, especially monitoring crop stress from pressures such as drought, disease, and pest insects. Their potential for use monitoring insects, however, is so new that sampling protocols have not even been developed. Nevertheless, the authors predict that collecting by drone can be faster and less labor-intensive than collecting by hand.

Profiling pest populations, the authors explain, is an essential first step in a robust IPM plan for a major agricultural operation. Insect populations must be scouted to identify pest species and determine how to time and style treatments for the most impact. As soon as crops emerge from the soil, growers need to monitor fields weekly to determine when the economic threshold for treatment is reached. Sweeping vegetation with a net is a time-honored method of surveying insects.

Sweeping an alfalfa field, to use an example presented in the paper, is hard work, sweaty if in the hot sun, leaving workers vulnerable to insect stings and bites and even, note the authors, snakebite. Typically, samplers use a net with a 15-inch diameter to take multiple 180-degree sweeps over different parts of the fields. The content of the sweep net is then placed within a plastic bag or jar, and insect counts are conducted.

The authors suspended a similar net from the iDrone Bee and used it to sample the western tarnished plant bug (Lygus hesperus), a serious alfalfa pest, in an alfalfa field. The drone crew consists of a pilot-in-command (PIC) who controls the device and a visual observer (VO) who watches for potential safety hazards such as collisions with other aerial objects, be they crop dusters or hawks.

“The procedure of the iDrone Bee takes about 3–5 minutes to collect insect samples while flying, but it depends on applications,” write the researchers. Protocols need to be developed to make optimum use of the drone, they say, and other features such as auto-pilot capabilities could be added to improve the accuracy of counts, especially in difficult terrain.

Ed Ricciuti is a journalist, author, and naturalist who has been writing for more than a half century. His latest book is called Bears in the Backyard: Big Animals, Sprawling Suburbs, and the New Urban Jungle (Countryman Press, June 2014). His assignments have taken him around the world. He specializes in nature, science, conservation issues, and law enforcement. A former curator at the New York Zoological Society, and now at the Wildlife Conservation Society, he may be the only man ever bitten by a coatimundi on Manhattan’s 57th Street.