CHICAGO — Here’s a heads-up to Chicago renters and condo dwellers: Your building managers know the Deadheads are descending on Chicago in July and they’ll be watching who’s going in and out of your building with suitcases.

The rise of Airbnb and similar online room-sharing services in Chicago — particularly during the summer months — has apartment high-rises and condominium associations clamping down on scofflaws.

More vigilance is coming, now that many downtown Chicago hotels are sold out during the Grateful Dead’s 50th anniversary concerts July 3-5, and steep rates are attached to the hotel rooms still available.

“Events like the Fourth of July holiday, there are going to be a lot of people in town that don’t necessarily have a place to stay,” said Michael Mini, executive vice president of the Chicagoland Apartment Association. “That weekend, which is pretty busy anyway, with the Grateful Dead concert, our members are certainly aware and they’re going to be very vigilant about policing their units.”

Managers may have their work cut out for them.

Compared with a year ago, Airbnb has seen a 46 percent spike in listings within the city of Chicago, to 3,800 listings from 2,600 in March 2014.

“The Grateful Dead is a good example but this problem erupts every summer,” said David Sugar, a partner at Arnstein & Lehr and co-chair of the firm’s condominium law group.

Airbnb last month began collecting and remitting hotel taxes in Chicago, and the city has a vacation-licensing procedure for people who want to rent even part of their apartments, condominiums or single-family homes. But most hosts offering their couches, spare bedrooms and entire units for rent do it under the radar by not putting their exact address in listings, using fake names and meeting visitors off-site to exchange keys.

Building managers are starting to catch on, and it’s not just a building’s air of exclusivity they are trying to protect. There also is the legal liability for both occupant and the building if something goes horribly wrong.

As a result, managers and other building employees are regularly checking room-sharing websites. In some cases, the locations are obvious from the map or from photos of rooftop pools and gym facilities, amenities that are paid for by year-round residents either in steep rents or association fees.

In one Chicago condo building, one of the job duties listed in the handbook for doormen is asking people who enter the building with suitcases what unit they’re headed to and how long they are staying.

The presence of lodgers can be particularly difficult to spot in smaller buildings with no doormen or security cameras. In some of those instances, neighbors act as whistleblowers to their management companies and city officials.