In higher education, they’re the equivalent of gig workers: part-time professors who power many of the area’s colleges, cobbling together teaching assignments each semester at one or two universities at a time.

Now, many are demanding that state legislators ensure they are paid adequately for their work and receive similar health care and retirement benefits as full-time professors.

Dozens of adjunct professors crowded into a room at the State House Thursday wearing buttons that proclaimed “equal pay for equal work’’ to make their case and back legislation that would dramatically increase their earning.

“We are paid poverty wages to do very important work,’’ Michele Nash, an adjunct professor at Springfield Technical Community College, told a panel of state lawmakers, urging them to support legislation that would also offer more protections for part-time public and private university professors.

Adjunct professors used to be working professionals who would teach an occasional university class. But colleges and universities, trying to reduce costs, have increasingly come to rely on them for everyday teaching. Adjunct professors now make up anywhere between a third to two-thirds of the faculty at Boston-area colleges.

Many said they teach similar classes to full-time professors but earn far less and receive less in benefits. The legislation, proposed by Representative Thomas Stanley of Waltham, would increase their pay to be similar to that a full-time instructor on a per-course basis. It would also require colleges to notify adjuncts earlier if courses are dropped and partially pay them for last-minute cancellations.

The Association of Independent Colleges and Universities in Massachusetts, which represents 58 schools, said the legislation is likely to increase the already skyrocketing cost of education. It also comes as higher education institutions are facing potential cuts in funding from the federal government in research and financial aid.

“It’s not good for students and the affordability and cost of college,’’ said Richard Doherty, president of the association.

Adjuncts are attempting to bypass the traditional collective bargaining process by going through the Legislature to get their pay and benefit increases, he said.

Officials with the University of Massachusetts Lowell, which is in the midst of negotiations with its adjunct faculty over pay and health insurance, said the university leadership has not taken a position on the legislation yet.

But UMass Lowell defended its compensation plans for adjuncts.

“Adjunct faculty teach about a quarter of all courses offered at UMass Lowell and play an important role at the university, but comparisons to positions at different campuses with different job responsibilities, job descriptions, and titles inaccurately conveys an equivalence that does not exist,’’ said Christine Gillette, a UMass Lowell spokeswoman.

It’s unclear how much of an increase adjuncts would receive in their salaries if the legislation passes, because full-time professors aren’t paid by the class and have other responsibilities, such as establishing curriculum and helping set student admission standards.

But the annual pay differences between full-time and part-time professors can be vast.

Adjunct professors earn between $2,900 to $5,500 to teach one course, depending on the college campus, according to Service Employees International Union Local 509, which represents human service workers and educators throughout Massachusetts.

Many don’t receive health care benefits through their job, and if they can contribute into a retirement plan they don’t always qualify for an employer match, advocates for adjuncts said.

The average annual salary of a tenured professor in New England was $120,559 in 2016, according to a yearly report from the American Association of University Professors. Meanwhile, universities on average pay part-time professors $20,508 annually, usually to teach about two or three courses a semester, according to the study.

The association noted in its report that even adjuncts who teach multiple courses at several universities at the same time would struggle financially.

Amy Todd, who now teaches full time at the University of Massachusetts Boston, said she spent several years as an adjunct, sometimes teaching at three different local campuses in a single day. The pay was so meager that she qualified for federal food subsidies, she said.

While she was fortunate to have gotten a more permanent job after several years, many more professors remain part time for decades, she said.

“There is a myth that adjuncting is temporary,’’ Todd said. “ But these jobs are not temporary.’’

Deirdre Fernandes can be reached at deirdre.fernandes@globe.com. Follow her on Twitter @fernandesglobe.