Shortly after boarding her Turkish Airlines flight from Johannesburg to Istanbul last March, Patience Titcombe, 36, from Phoenix, noticed a small bug crawling on her seat when she got up to use the restroom.

“I almost flicked it away,” she said, “But my friend stopped me and said, ‘That’s a bedbug.’” Ms. Titcombe, who had experience with the bugs when she lived in Philadelphia, realized her friend was right and photographed the bug on her seat.

She then called over the flight attendant, who disposed of the bug. When Ms. Titcombe and her friend confronted the flight attendant about its being a bedbug, she said, the attendant dismissed their concern.

“I had to strip down at the airport and change clothes because I have kids — what if I brought bedbugs home?” Ms. Titcombe said. She said her complaints to Turkish Airlines after her flight were met with denials, despite her photographic evidence. After posting about her experience on multiple social media channels, Ms. Titcombe said other users in a Facebook travel group reported similar experiences.

In October, two other travelers said they encountered bedbugs on the airline’s flights. On Oct. 5, Matthew Myers and his girlfriend were flying from Istanbul to San Francisco when Mr. Myers, 28, from San Francisco, said the passenger seated next to him tapped him on the shoulder to show him there were bedbugs on the seats and falling from the ceiling. Mr. Myers said he saw bugs fall onto the person’s lap. “Multiple passengers were asking to move seats after discovering bugs,” Mr. Myers said. According to his account, one passenger relocated to the flight attendant jump seat when bugs were seen falling from the ceiling. He said a flight attendant told the passengers she had filed an official complaint during the flight.

Three weeks later, Kristin Bourgeois, 37, a science teacher living in Malaysia, said she found bedbugs on the 10-hour flight from Washington Dulles to Istanbul. “Before departure, I noticed a bug crawling on my blanket,” she said. “When I found another on the pillow, I realized it was a bedbug.”

She documented 13 bite marks across her body after the flight.

For airline passengers, there are rules surrounding issues like delays and cancellations, but not for insect infestations. Passengers’ main recourse is through airlines’ customer service departments or, failing that, small claims court.

Turkish Airlines did not return multiple requests for comment.

Bedbugs are a recurring issue in travel. In late 2023, Paris faced a widespread outbreak at the height of its annual Fashion Week, when the bugs were seen on public transit and in other places. That same year, South Korea launched a nationwide prevention campaign targeting transportation hubs.

The bugs live in mattresses, bedding, carpets and clothing, and can easily be transferred in luggage. They typically bite at night, leaving clusters of bumps on the skin that can cause itchiness, redness and swelling and burning. They are also notoriously hard to get rid of, with people having to seal all their belongings in plastic bags or endure multiple fumigations.

Airlines face particular challenges with bedbug prevention and removal, as planes frequently move between climate zones and undergo rapid turnarounds between flights, potentially complicating traditional treatment methods.

Taking an aircraft out of service for bedbug treatment is a significant undertaking, according to Rob Tuck, the president of the aviation consulting firm Jet Research. “You’ve got to get it to a maintenance base, because not every location is a maintenance base,” said Mr. Tuck, who has worked in aviation for 36 years.

The process typically takes two to five days and can cost airlines between $75,000 and $125,000 when accounting for lost revenue and treatment expenses. “They do have a bit of a protocol to work from,” Mr. Tuck said. “You’ll pull the airplane out of service and you’ll bug bomb it.” But without a spare aircraft available for long-distance routes, airlines face difficult decisions, particularly when passengers report infestations mid-journey.

The passengers say Turkish Airlines’ response has been underwhelming. The carrier offered Mr. Myers a 10 percent discount on future travel, valid through December 2024, and said that aircraft undergo “deep cleaning every 21 days, and general cleaning before every flight.” This matched the compensation offered to an X user who claimed to have suffered bed bug bites on an August 2024 Turkish Airlines flight and shared photos with the airline’s help desk.

Ms. Titcombe reported her March incident using Facebook Messenger and email and she said the airline didn’t seem to be coordinating across channels, asking her to specify which flights were affected, even though she had already provided flight details. Later, it claimed “no record of any disruption” existed, though she had documented the incident with photos and reported it to the crew.

After Ms. Bourgeois filed her complaint, the airline said in an email that it required “a medical report approved by a doctor with signature, stamp and date” before investigating. When she attempted to follow up, Ms. Bourgeois said representatives claimed they couldn’t locate her reservation, then suddenly found it and hung up. Her flight history was then removed from the airline’s mobile app, she said. On Dec. 3, the airline offered Ms. Bourgeois 5,000 frequent flier miles if she couldn’t provide medical documentation.

Turkish Airlines operates nearly 400 airplanes and serves more than 300 destinations. The carrier flies to several American cities, including New York; San Francisco; and Washington, D.C., operating multiple flights daily between the United States and Turkey.

“The struggle here for an airline is very complex,” said Mr. Tuck. “To take an aircraft out of service, that’s not chicken feed. But the desire to have a good cabin experience comes from the top.”

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