Hamza Saleem stared out at the mostly empty tables inside the Subway he manages at Hudson Mall. Only a handful of customers walked through the white-tiled halls of the Jersey City mall on Friday and they were nearly outnumbered by the patrolling security guards.

“There’s nobody in the mall on Friday," he said, gesturing to the vacant hallway. "It’s supposed to be really busy.”

The mall’s vendors are struggling with an almost invisible menace: an infestation of gnats caused by a broken sewer pipe. Though harmless, these tiny insects are having an outsize impact on the vendors’ bottom line, they say.

Amir Saad, an employee at Father Yostos Gift Shop, said he sprays the shop with Raid every day “just for me, just to work." A smoking stick of incense on the checkout counter did not fully mask the chemical smell. Next to the counter, a glowing insect trap buzzed. Saad said he emptied the dead flies out four or five times every day.

“Day by day it becomes more and more,” he told the Jersey Journal. “It became terrible.”

Vendors say the gnats have infested the mall for several months. The insects have driven away customers, and as a result, business has dropped precipitously, some said.

“As soon as me and my friends walked in, I had a fly, flying around me,” one person wrote on Yelp. "And they’re not big ones, they’re little fruit flies, but still nasty.”

Urban Edge Properties, the real estate company that owns Hudson Mall, told The Jersey Journal in an email that a leaking sewer pipe has brought on the bugs.

“We immediately took action to uncover and replace the broken section of pipe. We worked closely with both the Jersey City and Hudson County health departments, seeking their guidance and assistance, and are continuing to follow all of their recommendations,” Urban Edge’s vice president of asset management Bassam Mhich said in an email. “Significant positive results have been achieved and we will continue all remediation efforts until conditions at the center are returned to normal.”

Jersey City spokeswoman Kimberly Wallace-Scalcione said the city health department has been involved since Dec. 30.

“Health officials coordinated with mall management to rectify the issue using specific traps that were determined to be the most effective and safest solution,” Wallace-Scalcione said in a statement. “Health officials are monitoring the establishments on a daily basis.”

The manager of a gift shop called Good Fortune, who declined to be named, said that customers had stopped coming to his store, complaining about the bugs.

In early January, Jersey City health inspectors ordered him to turn off ornamental fountains that he sold and remove potted bamboo plants from his store. The inspectors told him that they were exacerbating the problem, the manager said.

“I’ve been selling plants for 20 years,” he told the Jersey Journal, adding that the flies had only been around for a few months. When the inspectors came back four days later, after the plants had been removed, they issued another Good Fortune employee a court summons on the grounds that she had interfered with a health officer, a penalty the manager said was unwarranted.

“It’s not our fault," he said. "We suffer for months already.”

Urban Edge has conducted one-on-one meetings and provided regular updates to mall vendors, the statement added.

“We would like to thank our tenants for their support, patience, and accommodating our repeated inspections. And of course, thank our customers for their understanding and loyalty,” Mhich said.

But Ibrahim Hesham, who works at a men’s clothing store at the mall, said the flies have driven away customers.

“Bad business, bad, bad, bad,” he said. “Nobody come now. If you look outside, nobody is walking.”

On Friday, some businesses were closed, and those that remained open were almost completely empty. Vendors were divided on whether or not things had gotten better since repair work on the pipe began. And the damage may have already been done.

Juan A. Martinez, who owns the restaurant Pizza Palace, said that with the decreased sales, he wasn’t sure he would be able to keep the business open.

“We have no money to pay the rent,” he said. “What can I do?”