The creepy creatures that lurk ominously inside closets and beneath beds are not entirely fictitious.

While bed bugs and rodents grip adult homeowners with fright much like Sully and his crew of havoc-wreaking monsters from “Monsters, Inc.,” the patent of their scariness lies not in their enormity or ferociousness but in their subtlety — their capacity to hide in cracks and crevices: dark recesses of box springs, behind baseboards, in squeaking drawers and tiny water pipes.

Bed bugs and rodents might frighten renters, but they seriously affect a home. With knowledge of these pests, how to prevent them and the means to exterminate them, residents can feel confident in their home’s livability.

Though there is no complete defense system, there are simple and cost-effective pest prevention techniques. An insect interceptor, which can be placed beneath the legs of a bed, impedes bed bugs’ journey toward a bloody meal by trapping them in what “resembles a plastic ashtray with a moat,” according to Bill Todaro, an entomologist for the Allegheny County Health Department.

Avoiding rats is a simpler task, rooted mainly in basic domestic upkeep and maintaining a “comprehensive effort to eliminate the things that rats are attracted to” such as food and garbage, Todaro said.

Since bed bugs depend on the transport of a host — the reason why they are so prominent in hotels, where there is a constant circulation of humans — and hitch rides in their prey’s coat pockets or luggage, defense techniques are often enacted too late, especially because the infestation of an apartment could have begun on a different continent.

When you have an infestation, however, one of the most obvious symptoms exploits a singular flaw in the pest’s camouflage, something a homeowner can detect without seeing: odor. Bedbugs, whose Latin name literally means “bug of the bed,” smell sweet like berries while rats smell rank like ammonia, according to the Centers for Disease Control’s website. These smells, coupled with a few other telltale signs (small, reddish welts for bedbugs; chewed wires and small holes in your house for rats) can indicate that you’re housing some freeloading and destructive roommates.

Despite the negative connotations that surround having a bug infestation, bed bugs “have nothing to do with social class or cleanliness of the structure where they are found, and anything that produces carbon dioxide is a target,” said Shawn Linnan, the chief operating officer of Affordable Extermination Services of Pittsburgh.

According to the CDC, bedbugs do not spread diseases and — aside from causing itching and loss of sleep — are fairly benign.

Rats, however, according to the CDC, can spread up to 37 diseases, including salmonella.

“Any animal that is at home in a sewer” — one of the common ways a rat may enter a home — “spreads bacteria and pathogens in a house,” Todaro said.

Rats are attracted to wet and warm environments and can find comfort under kitchen sinks and basements, entering through holes as small as a quarter in a house’s foundation.

Instinct might instruct a rash and immediate removal of these pests, with home-safe bug repellents, mousetraps, and some fervent vacuuming, but according to the Allegheny County Health Department, a thorough inspection and removal of pests by a professional is the safest way to thwart their spread and destructiveness.

Elizabeth Pabor, a Pitt senior, discovered some rats living beneath her sink last year and was “scared about her kitchen being sanitary,” she said. In an attempt to exterminate the rats, she purchased no-mess mousetraps, which failed to help, and eventually she had to contact an exterminator.

“If you have an infestation, contact your landlord or professional pest control company,” Linnan advised.

Do-it-yourself techniques, including washing sheets, vacuuming for bedbugs and setting up traps for rodents, are not thorough enough.

“It requires a comprehensive pest control effort. In apartments and condos they are hard to get rid of,” Linnan said.

The CDC suggests speaking to a landlord so that he or she can inspect the spaces of all adjacent neighbors. While getting rid of an infestation can be difficult, professional pest-control experts provide the best hope for assuring that your unwanted housemates are gone for good.