Betsy Neal is looking for someone who cooks, someone who doesn't, someone on the night shift, someone who'll be around for lunch - and someone who wouldn't mind living with 200 grasshoppers.

"This is the time of year when I chain myself to the desk," said Neal, the 32-year-old cofounder, coowner, and sometime mother hen of Roommates Preferred. Now in its fifth year, her roommate referral agency on Capital Hill introduces the haves and have-nots, to groups whose numbers swell here during the dog days of August.

"It's like going to a class reunion," Neal said yesterday lounging near the fireplace in her homey office at 702 Independence Ave. SE, where she shares a house with roommates picked through her referral service. In August, old clients call up and she gets to catch up on how past arrangements have worked and what future arrangements are needed.

After a few years in the business, Neal knows when different sorts of people start their search. This year, she says, the student interns flocked in late.

"It sound like I'm talking about birds," she said with a giggle.

With the exception of brief dashes across the street to grab a sandwich or a cup of coffee, Neal stays near the phone from 9 to 8 on weekdays and 11 to 3 on Saturdays. But the nature of the work, she says, makes it a round-the-clock concern: "You're always thinking, "Gee, I wonder how Rosemary's doing, she's only got one more day before she has to move.""

Every person who wants to use the service must come in for an interview with Neal. She talks with them about their preferences, tells them what she has available and lets the "personal instinct" that she's developed for who will get a long with whom to to work.

If a client decides to register, he or she pays $30 per roommate or place sought, which buys access to the file - and Neal's instinct - for as long as the search may take.

Most customers ask hesitantly if they're being too picky when they cite their preferences, Neal said. Others present stiff requirements. A few years ago a "fruitarian" dropped into the service. Neal dutifully checked to see if she had anyone who had sworn off both meat and vegatables.

"I told him I didn't have any fruitarians on file," she slyly told him.

Then there was the woman who wanted an overweight roommate who wouldn't borrow her clothes. And there was the man who had to turn down a female housemate. Neal suggested because, well, he had just broken up with her. And there were the two women in Virginia who discovered after they were matched that they were also cousins.

As for the fellow with the grasshoppers, Neal thinks she's found a place for him and his collectables. "He doesn't have any furniture," she recalled, "but he has more comic books than he has grasshoppers."

Once in a while, people come in thinking that becamse the service handles many coed house-sharing arrangements, it's an inexpensive way to start a new romance.

"We are not in any way, shape, form, manner or size a dating service," she declared.

Neal said the best dividend of her work probably has been the opportunity to watch people drop the masks they wear in public.

Because they rely on her to set them up with compatible roommates, she said, they don't pretend. More often, they dump the details of their lives in her lap.

"When they say, "I'm not going to tell you about the divorce thing,"" she said, "that's when I set back and light up a cigarette." CAPTION: Illustration, no caption.