As stay-at-home orders swept across the country, shoppers rushed to grocery stores and stocked up on staples, among them eggs. This spike in demand has boosted egg prices, and likely will for some time.

On March 2, the Urner Barry wholesale benchmark for a dozen conventional California shell eggs was $1.55. By March 27, the benchmark rose to $3.66, where it remained for several days before decreasing slightly to $3.26.

That means higher costs for retailers — and also shoppers. The California Grocers Association described it as one of the largest increases in a while.

"We are still receiving eggs in our shipments, but egg supply fluctuates and not all brands may be available every week," said Hy-Vee spokeswoman Christina Gayman.

Lunds & Byerlys also said it had an ample supply heading into a holiday weekend.

Agricultural experts describe the price increase as a lesson in supply and demand.

There's only a fixed number of eggs available on any given day — you can't squeeze an unlimited number of eggs out of a chicken, and it can take months to buy more hens and build more coops for them.

In the meantime, shoppers are clamoring for extra cartons as they aim to limit grocery runs amid the coronavirus pandemic.

Some retailers have purchased double or even six times their usual orders of eggs, said Brian Moscogiuri, director with Urner Barry and an analyst covering the egg and egg product markets. To try to keep eggs in stock, some stores posted limits on the number of egg cartons customers could buy.

That's the case at Beachwood Market in the Hollywood Hills, Calif., where owner Alex Papalexis said he had to limit customers to one carton per household.

Many restaurants and hotel kitchens are closed, meaning eggs destined for diners' dishes could now be diverted to store shelves, Papalexis said.

"There's a question there." Papalexis said. "Why would they have to raise their rates?"

Prices for eggs certainly have risen more than 10% in many markets, but it's hard to gauge all of the factors that might contribute to that increase, said Diana Winters, assistant director of the Resnick Center for Food Law and Policy at the UCLA School of Law.

For example, restaurant closures could mean egg producers need to divert their supply to grocers, and that change in distribution and additional packaging comes with a cost.

"Eggs are naturally, very often, one of the most price variable products in the supermarket," said Daniel Sumner, University of California, Davis professor of agricultural economics and director of the UC Agricultural Issues Center.

Jesse Laflamme, chief executive of New Hampshire-based Pete and Gerry's Organic Eggs, said his freight costs have gone up since the coronavirus pandemic because there are not enough refrigerated trucks to transport all of the fresh goods now in high demand.

Egg prices could remain elevated for at least a few months, Sumner said. And the demand for eggs has been historically strong during tougher economic stretches. Eggs are a relatively cheap source of protein and aren't seen as a luxury food item.

"It may take longer to get back to normal for the egg business," he said. "We can build supply, but it takes a few months."

Includes reporting by staff writer John Ewoldt.