They're unwanted house guests who drop in and won't leave.

Whether it's cockroaches, ants, mice or rats, you might need to hire a professional to deal with them.

If you have a pest problem, do your homework or you could get bitten by that pest control company.

Like any other service, pest control companies vary in quality and price.

When Puget Sound Consumers' Checkbook magazine surveyed local firms, they found that prices for pest control vary greatly.

The magazine's researchers shopped for a one-time treatment for cockroaches in a local home.

The estimate ranged from $145 with a 90-day guarantee to $500 with no guarantee. And, as it turns out, the magazine's survey showed you don't have to pay top dollar to get the job done right.

When it comes to household pests, there can be a number of ways to attack the problem. That's why it's important to have several firms come to your house.

"You want to get several firms to come and say, 'yes, this is the problem, this is how we're going to treat it.' And then compare prices for the treatment and compare that guarantee that they'll give you after the treatment," said Robert Krughoff with the magazine.

Ask how the problem will be handed -- will they use bait and traps or will they use poison? The answer will affect how many chemicals you'll be exposed to, and whether you'll need to leave the house.

Anyone whose used one of these companies know that they may not get the problem taken care of the first time. That's why important to know whether the company you choose guarantees its work.

"Find a firm that will promise to do it in one treatment and that will charge you little or nothing to come back if a second treatment is needed," said Krughoff.

Based on the magazine' s survey of customers in the area, only five companies got top marks for price and quality. They are:

AARD Pest Control in Lynnwood

Able Pest Control in Kent

Alderwood Pest Control in Seattle

Regiment Pest Control in Woodinville

Sprague Pest Solutions in TacomaOne more thing to consider before you call a professional: check to see if the problem is something you can take care of on your own.

If rodents are using holes to get into the house, seal them. If the problem is caused by sanitation issues or moisture, deal with the cause and the pests should go away.

You can find the complete list of recommended companies in the fall/winter 2007 issue of Checkbook magazine.