Paper wasps are often mistaken for scary hornets, but they rarely sting people and are beneficial insects welcomed by farmers because they eat pests that ruin crops. U.S. scientists have succeeded in wirelessly tracking where these helpful, agriculture-saving wasps go, thanks to attaching an RFID electronic tag lighter than dew on their backs.
On the 9th (local time), Spectrum, published by the Institute of Electrical and Electronics Engineers (IEEE), reported that a University of Michigan engineering team developed a 20 mg (milligram, 1 mg is one-thousandth of a gram) electronic tag to attach to paper wasps and successfully tracked their movements. That weight is only one-third of a drop of water.
The ultralight electronic tag is the result of research by David Blaauw, a professor in the Department of Electrical and Computer Engineering, and Professor Kim Hoon-seok. Yi Shen, a doctoral researcher, said on Feb. 18 at the IEEE International Solid-State Circuits Conference in San Francisco that they successfully tracked the flight paths of paper wasps released on campus with the electronic tags attached.
The team set a goal to track paper wasps within a 1.45 km range with a 0.9 m margin of error using an ultralight transmitter. Professor Kim Hoon-seok said they optimized everything from the integrated circuit (IC) chip design of the electronic tag to the algorithm, making it lighter and enabling it to operate over a wide area while using less power. An algorithm is the software "brain" that tells the hardware chip in what steps to process data, determining the efficiency and speed of computation.
◇Research on pollinating insects essential to agriculture
Learning where and how insects spend their time is crucial because insects underpin the food chain in ecosystems and help pollinate crops. According to the Food and Agriculture Organization (FAO), 71 of the world's top 100 crops rely on insects for pollination. Paper wasps also seek nectar from flowers and aid pollination, and they even hunt the larvae of pests such as gypsy moths and flies.
The problem is tracking insects. Ants can be raised in a lab to study how they live in their nests. Bees have been painted with different colors on their backs to learn how they live socially in the hive. But once insects leave home and fly off, they are hard to study. Scientists have attached electronic tags to the backs of flying insects to track their movements. An electronic tag developed by Cellular Tracking Technologies (CTT) in the United States is a representative example.
CTT's 60 mg electronic tag has been used to track the migration routes of monarch butterflies, which are known to fly the longest distances among insects. In winter, they travel more than 4,000 km from the northern United States and Canada to Mexico. When spring comes the following year, their offspring born in Mexico head north again.
To reduce the weight of the electronic tag, CTT attached a capacitor and a solar panel instead of a battery. A battery generates current by moving charged particles, but a capacitor stores charge directly between two conductors, allowing that much weight savings.
◇Lighter weight with battery substitution and circuit optimization
The University of Michigan team also developed an electronic tag in 2000 for tracking monarch butterflies. The M3 electronic tag developed by Professor Blaauw's team was a fully energy-autonomous computing system and weighed only 50 mg, 10 times lighter than the then lightest electronic tag.
Korean scientists led the development of the ultralight electronic tag. Professor Lee In-hee in electrical and computer engineering handled chip and system design, and Professor Kim Hoon-seok designed the algorithm to analyze data and reconstruct individual movement paths. Professor André Green of the Department of Ecology and Evolutionary Biology analyzed the movement paths to study the biological characteristics of monarch butterflies.
Even with weight reductions, 50–60 mg electronic tags burden paper wasps. Monarch butterflies have a wingspan of 90–100 mm, but paper wasps are only 18–25 mm long. They weigh just 125 mg. Attaching an electronic tag to such a wasp is like asking a person to carry a backpack weighing about half their body weight. The University of Michigan team cut the tag's weight to about one-third so paper wasps could handle it.
The University of Michigan team also chose a capacitor instead of a battery. Professor Blaauw explained, "Batteries are hard to make smaller, but capacitors that accumulate charge on surfaces are suitable for miniaturization." The capacitor on the tag attached to paper wasps weighed only 0.86 mg. The tag's solar panel charges the capacitor to generate enough energy to send a wireless signal. Professor Kim Hoon-seok's algorithm optimization also lightened the tag.
Professor Kim said the ultralight electronic tag could be used not only for ecological research but also for the Internet of Things (IoT). "It is much smaller and lighter than Apple's AirTag, an electronic tag used to find lost items, and it uses less power, so it could be used in a variety of places," Kim said.
Professor Kim Hoon-seok graduated from Seoul National University and earned a doctorate from the University of California, Los Angeles (UCLA). He has been a professor at the University of Michigan since 2016. He received the Defense Advanced Research Projects Agency (DARPA) Young Faculty Award in 2018, the National Science Foundation (NSF) Faculty Early Career Development Award in 2019, and the Sony Faculty Innovation Award in 2024.
Professor Lee In-hee, who developed the ultralight electronic tag with Professor Kim, graduated from Yonsei University and received a doctorate from the University of Michigan. He served as a professor at the University of Michigan starting in 2014 and moved to the University of Pittsburgh's Department of Electrical and Computer Engineering in 2019.
References
IEEE International Solid-State Circuits Conference (2026), DOI: https://doi.org/10.1109/ISSCC49663.2026.11409200
Communications of the ACM (2024), DOI: https://doi.org/10.1145/3611105