Mid-August through mid-October is the best time to eat steamed crabs, such as these from Harris Crab House in Grasonville, Md. (Marvin Joseph/The Washington Post)

Some of us grew up eating crabs at backyard feasts, whacking the bright red shells with wooden mallets and pinching younger brothers with discarded claws. But for many, going to a crab house for the first time can be confusing — and that’s before your friend explains why his crab-picking style is the most efficient.

Here are the answers to some commonly asked questions.

When is the best time to eat crabs?

Now through mid-October. The crustaceans have spent the summer growing, molting and fattening up, which makes them more fun to eat than the skimpy little crabs that are common around Memorial Day.

When I sit down at a waterfront crab house, I’m eating Maryland crabs, right?

Maybe. Maybe not. The dirty secret of some area crab houses is that while the kitchen might be only miles from the Chesapeake Bay, the crabs have traveled much farther: Those blue crabs or swimming crabs were spawned in the Gulf Coast, Indonesia, Vietnam or Venezuela.

The primary drivers for this are price and supply: Maryland’s crab population is climbing again, but the state produced 33.1 million pounds of crabs in 2015 — far from enough meat to feed all of the region’s hungry crab lovers. This pushes up prices for restaurants that are willing to pay more for a local product, and means that some restaurants can’t afford to carry Chesapeake Bay crabs if they want to turn a profit. This is compounded by the short crabbing season: In Maryland, it’s legal to catch crabs only from April 1 to Dec. 15.

Harris Crab House in Grasonville, Md., is a “True Blue” restaurant. (Marvin Joseph/The Washington Post)

How can I tell if I’m eating Maryland crabs?

The easiest way is to check the list of “True Blue” restaurants on marylandseafood.org. To participate in the True Blue program, which was launched in 2012 by the Maryland Department of Natural Resources, a restaurant must promise that at least 75 percent of the crabmeat it uses each year will be “harvested and/or processed in the state of Maryland.” Every business that makes the pledge provides the DNR with invoices proving that its crabs were purchased from local wholesalers or watermen before it’s listed on the True Blue website.

Karen Knotts, who manages True Blue for the DNR, stresses that the program — which has grown to more than 160 members in Maryland, the District, Virginia and Delaware — is “promotional, [and] not a certification program.” The state doesn’t use forensic tests to prove that the meat comes from Chesapeake blue crabs. Instead, restaurants are randomly audited a few times each year and asked to show proof they’re purchasing crabs from local watermen. If a restaurant isn’t in compliance, it can be removed from the program, but there are no further penalties.

It’s worth noting that you can eat local crabs at a restaurant without True Blue status. Some popular crab houses serve Maryland crabs throughout the summer, but rely on Gulf or imported crab in spring, when catches are light, as well as throughout the winter, which pulls them below the 75 percent line.

What do the different sizes of crab (#1s, #2s, jumbo) on the menu mean?

They mean whatever a restaurant wants them to mean. There is no standard size guide, other than Maryland’s legal minimum, which is 5¼ inches. Some places will tell you that the largest and heaviest crabs are #1s, crabs that are a bit smaller are #2s and so on. Others use more conventional terms, such as “small, medium, large, jumbo.”

But even those descriptions vary from crab house to crab house: At Jimmy Cantler’s famous crab house in Annapolis, for instance, a large crab is 6 to 6 1/2 inches, while across the bay at Ocean Odyssey in Cambridge, a large is between 5 1/2 and 6 inches.

Size doesn’t always matter. I recently enjoyed some medium (about 5 1/2 inch) crabs in Annapolis that were packed with more sweet, delicious meat than the larges (6 to 6½ inches) I’d had the week before in Baltimore.

Nicholas Hudec, 5, uses his mallet to get to the meat of his steamed crab at Quarterdeck in Arlington. (Marvin Joseph/The Washington Post)

So how many crabs should I order?

A good rule of thumb is three to four crabs per person. Order fewer if you’re also ordering corn, hush puppies, oysters and other appetizers. And while size varies between restaurants, you can usually trust the crab houses to rank the crabs appropriately: four mediums is probably equal to two or three larges, which are equal to one jumbo or extra-large. It depends on how hard you want to work for that precious lump meat.

Keep in mind that at good crab houses, crabs are steamed to order. If you get halfway through your order and realize you want more, you’ll be looking at an at least 30-minute wait before the rest of your meal arrives. When in doubt, order an extra crab. Someone will eat it.

Where’s the drawn butter?

You’ll automatically get little cups of apple cider vinegar or extra seasoning for dipping your crabmeat at most Maryland crab houses. If you want to look like a tourist, ask for drawn butter to go with your steamed crabs. (Or worse, tartar or cocktail sauce.) Save the butter for king crab legs or lobster.

What beer goes best with crabs?

Most crab houses around the Bay serve National Bohemian, even though the Pabst-owned lager hasn’t been brewed in Maryland for two decades. For a local pairing, try Anthem, a sweet, golden ale from Baltimore’s Union Craft Brewing, or Stillwater Classique, a lemony, peppery beer that is a “deconstructed” twist on Natty Boh. For a more flavorful experience, order Dead Rise, from Frederick’s Flying Dog. Brewed with Old Bay crab spice, the summer ale is crisp and salty, with notes of pepper, allspice, and celery and garlic salts.