In Australia, Just One Wasp Can Ground an Airplane With a Strategically Placed Nest

Invasive keyhole wasps were building nests in the equipment pilots use to measure how fast they’re flying

Close-up photo of a keyhole wasp sitting at the tip of a gray 3D-printed pitot tube
A keyhole wasp can block up an airplane's external sensor in as little as 30 minutes. House et al (2020) PLOS ONE, CC BY

New research conducted at Brisbane airport shows how the invasive keyhole wasp builds their nests over important sensors, causing havoc for aircraft, George Dvorsky reports for Gizmodo.

Keyhole wasps like to lay their eggs in small, pre-made cavities like window crevices, electrical sockets and, as their name implies, keyholes. Airplanes, meanwhile, rely on external sensors that are shaped like thin tubes. If the pilot realizes after takeoff that a sensor is blocked, the plane just has to turn around so it can be cleaned. But in a worst-case scenario, malfunctioning sensors are catastrophic. The new study, published on November 30 in the journal PLOS One, confirmed keyhole wasps are the sensor-blocking culprit, figured out their favorite size sensors for nest-building, and found that they built most of their nests near a grassy field at the airport.

The researchers hope that airports will be use the data to better combat the six-legged saboteurs.

"When we did some background research we realized that this wasn't just an inconvenience, that you just had to clean these things out and swat the wasps away; this could actually lead to major accidents," says Eco Logical Australia ecologist Alan House, lead author on the new study, to CNN’s Hilary Whiteman.

A plane crash off the coast of the Dominican Republic in 1996 that killed all 189 passengers and crew was linked to blockage of the pitot tube, which measures the speed that air is flowing through it as a proxy for how fast the plane is flying. The pitot tube’s measurements can show if the plane is flying fast enough to be stable, or if the plane is flying too slow, putting it at risk of stalling. Inaccurate airspeed readings can cause dangerous reactions by the pilots—or software.

“It’s not a Mayday emergency but it’s the next level down, and it closes the runways,” says House to New Scientist’s Donna Lu.

The wasps are native to the Americas, but have been flying around Brisbane for over a decade. The insects have figured out a speedy strategy for establishing their nests.

"We have anecdotal reports from ground crew at Brisbane that a plane can have arrived at the gate and within a matter of two or three minutes, a wasp will be flying around the nose of the plane having a look at the probe," House tells CNN. House adds to Belinda Smith at ABC News Australia, "When the plane first comes in, those probes are too hot for the wasp, so I think what she's doing is waiting for it to cool down.”

Once the tube is cool, the wasp fills the cavity with mud, an egg and a bit of prey, like a caterpillar. A thin wall of mud at the front seals the nest, and solidly blocks the pitot tube. This process can happen in under 30 minutes, as was the case when a wasp nest blocked the temperature probe on a flight from Brisbane to Newcastle in 2015, per ABC News Australia.

Most airlines have instituted rules requiring their planes to cover external sensors when they land at Brisbane airport, so House emphasizes that flying from Brisbane is generally safe, reports New Scientist. But to better understand the wasps’ behavior, House and the research team 3D-printed replicas of pitot tubes to mount at strategic points around the airport.

The team monitored the tubes for 39 months, between 2016 and 2019, and found 93 blockages, all in tubes larger than a tenth of an inch wide. The wasps built nests all year, but the team saw the most activity between November and May. All of the nests were located near a grassy field at the airport.

Brisbane airport wildlife manager Jackson Ring, a co-author on the study, tells CNN that the wasps probably rely on the field for the grubs they stuff into their nests. With that in mind, the airport has started spraying the field with pesticides and has already seen a reduction in wasp activity.

While all of the nests that the researchers found were built by keyhole wasps, not all of them housed keyhole wasp young. One nest hatched with five cuckoo wasps. These parasitic insects lay their eggs in other animals’ nests.

They’re native to Australia, so the fact that cuckoo wasps disrupted a keyhole wasp nest is actually "a real positive,” says University of Adelaide wasp taxonomist Erinn Fagan-Jeffries, who was not involved in the study, to ABC News Australia.

Often, invasive species can take over an area because they face no threats in their new environment, but Australian insects beg to differ.

“It means that some native Australian parasitic wasps are able to attack this introduced species," Fagan-Jeffries tells ABC News Australia. "There's a chance that those native parasitoids might be able to help keep the invasive wasp populations low and stop them from spreading too fast.”

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