The national egg shortage, which has caused wholesale egg prices to skyrocket over the past month, now is making a mark on the grocery aisle.

H-E-B is limiting customers to three cartons of eggs — whether they contain six, 12, 18 or 36 — to minimize the effect of the shortage, which is the result of a rash of avian flu in the Midwest.

The new rule, enforced by signs at all of H-E-B’s Texas stores, is meant to discourage commercial purchases of eggs from the grocery chain. That way, the eggs will stay available for consumers, spokeswoman Dya Campos said.

“Our goal is to assure families that our eggs are for them,” she said.

H-E-B’s announcement comes three days after Whataburger shrank its breakfast hours to protect supplies of its egg-based dishes, including taquitos and biscuit sandwiches. The burger chain said it was trying to replenish its egg stock after its primary supplier was “one of the hardest hit” by the shortage.

Managers of independent grocery stores in San Antonio said they haven’t been hurt badly by the egg shortage — yet.

On Thursday morning, only two or three cartons of eggs were left at Molina’s San Antonio Country Store downtown. Jacqueline Montalvo, the grocery’s kitchen crew leader, said the store hasn’t had to ration its eggs or raise its prices.

The price that Molina’s pays for eggs has gone up, though, from $26 for 15 dozen on May 18 to $36 this week. The store might have to raise its prices soon, at least for a short time, Montalvo said.

“I see the news and I say, ‘Uh-oh,’” she said.

Uncommon Fare, a grocery in Southtown that sells locally grown food, gets its eggs from a farmer in Hondo. The store has raised its price for a carton of eggs by a few cents during the shortage, assistant manager Diana Martinez said. Customers don’t seem to mind; they’re willing to pay a little more for fresh eggs, she said.

Several small farms harvest eggs in the San Antonio area and bring them to local farmers markets. Lori Hartman, owner of the 2-acre Hartman Farms in Stockdale, hauls about 100 dozen chicken, duck and goose eggs a week to the Pearl Farmers Market, along with peppers, carrots, tomatoes, squash, broccoli, collard greens and other vegetables.

Hartman hasn’t noticed an upswing in demand during the egg shortage. “Of course, this weekend might be a little different,” she said.

Avian flu broke out in Midwestern states in early April, according to the U.S. Department of Agriculture. Since then, the flu has been found in 48 commercial chicken populations, afflicting almost 38 million chickens.

The outbreaks have doubled the warehouse price of eggs in the past month. The price of a carton of large eggs in the south central region, which includes Texas, ranged from $2.44 to $2.52 on Monday, according to the USDA. A month earlier, it was $1.13 to $1.21.

H-E-B has joined others in the industry and raised the price of its eggs, Campos said, adding that the company was selling the eggs at a loss. Usually, the company tries to keep egg prices stable despite the volatility of the wholesale price of eggs, she said. It has an “egg procurement team” that looks for ways to improve the way the grocery chain gets its eggs.

Stable egg prices are important because the cost of basic commodities such as eggs and milk help determine where consumers decide to shop, Campos said. But the prolonged shortage has nudged the grocery chain to raise its prices.

Liquid egg products are in short supply, but the grocery chain isn’t currently setting limits on them. Wholesale prices, however, have gone up, she said.

“It’s abnormal, and we think that the market will level out soon,” she said.

It’s hard to say how much longer egg prices will go up, said Maro Ibarburu, an associate scientist at the Iowa State University’s Egg Industry Center. He pointed out that cases of avian flu have been detected in the past week.

“It is going to take some time to repopulate the facilities that have been afflicted,” Ibarburu said.

The length of the shortage will in large part determine how much of the increasing wholesale prices will be passed on to consumers, he said.

Walmart, which has 15 stores in San Antonio, doesn’t plan to limit its egg sales, spokesman John Forrest Ales said Thursday. The company has tinkered with its massive distribution network to prevent shortages, he said.

“We have tons of suppliers, so we’re pretty good at sending items where they have to go,” he said. “It’s a really important Walmart strength.”

Ales isn’t sure whether Walmart has raised its egg prices. The price “is going to go where the market goes,” he said.

Representatives of Whole Foods and Trader Joe’s didn’t respond to requests for information about their egg offerings.

One thing helping Texans is that it is hundreds of miles from the states that have been slammed by the avian flu — Iowa, Minnesota, South Dakota and Wisconsin. That has protected it somewhat from the egg shortage, Campos said.

That can be seen in the USDA data, which show that wholesale egg prices have gone up less in the past month in the south central region then in the Midwest and the Northeast, but more than in the Southeast, which includes South Carolina, Georgia and Florida.