Some squirt fluid, others can fly: How to keep cockroaches out of your home and avoid infestation

They're fast. Some can fly. And if you see one, you're likely to find more hiding in the nooks and crannies of your home.

They're cockroaches, and experts say they can cause significant health issues if not dealt with properly, including allergies and contaminating common and cooking spaces.

Nationwide, the cockroach species that poses the biggest threat are German cockroaches, said Benjamin Hottel, a board-certified entomologist and technical services manager with Orkin.

German cockroaches are smaller and are mainly issues in restaurants and multi-unit housing.

"(People) could bring them in on food items from a grocery store that had them, maybe from their work," Hottel told USA TODAY. "They could come in their backpack or their purse from work if they work in a restaurant that has them. These cockroaches can get spread around pretty easily."

He and other experts say there are ways to protect your home, though. Here's what to know.

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When are cockroaches most active?

Cockroaches' activity depends on the temperature, said Changlu Wang, a professor in the department of entomology at Rutgers University.

Take oriental cockroaches, for example. They're more likely to be active during the summer, while German cockroaches – most common in the U.S. – are active year-round.

"And here in the U.S., we have a very good heating system," Wang said. "Room temperature is maintained around 65 to 70 degrees Fahrenheit. That's actually optimum for cockroaches to develop."

Another common species that is much larger in size is the American cockroach, said Hottel, from Orkin. They're mostly in sewer systems and tunnels.

"When things are warmer, you tend to get more outdoor cockroach activity," Hottel said. "But for the ones that are already inside such as German cockroaches or American cockroaches in sewage systems, they can still be active in the winter."

And in the south, like Georgia, the smokybrown cockroach lurks around outside, usually in mulch, but it can also make its way into crawl spaces and attics. Smokybrown cockroach activity tends to wind down as the weather cools down, he said. They're more common during warmer seasons.

How do cockroaches get inside in your home?

Cockroaches typically make an appearance when there are sanitation problems in restaurants or in apartments, said Hottel.

Perhaps there's food or water that's easily accessible for them.

"In older facilities, it can be even more common because they tend to have more structural problems ... and older plumbing," he said.

They can even come into your home through pipes in your bathroom sink, he said.

It you take a peek under your sink, there's a looped pipe called a p-trap, he said. It holds water to prevent sewer gas from getting into the bathroom or shower area.

If that piping dries out, sewer gas and roaches can come through.

"Sometimes you'll get cockroaches coming up through pipes, or pipes rusted through," he said. "Once they get out and into a bathroom area or an office area, because there's not a humid environment, there's not a lot of food for them there, they end up just running around and dying."

But many cockroach species have no interest in coming inside the house, Hottel said. Often times, they come in because they're attracted to light or were brought in through potted plants that were carried into homes.

Peridomestic cockroaches, like the smokybrown cockroach, live outdoors or under houses and occasionally get inside "into areas that they shouldn't be," Hottel said.

"They're not really feeding on anything in the kitchens or anything. They're feeding on decaying stuff under the decks and maybe under people's houses or maybe even in attics," he said.

Can cockroaches fly? Yes, and some squirt fluid

Some cockroaches can even fly, while others can squirt out fluid as a defense mechanism.

Asian cockroaches can fly and occasionally get into people’s homes.

"Usually Asian cockroaches are attracted into a house when a door or unscreened window is left open and there is a light on in the house," Hottel said.

However, Hottel said, "They would not infest a person’s home like German cockroaches and are mostly found outdoors under leaf litter in the Southeast USA."

Florida woods cockroaches, Hottel said, can shoot a "defensive secretion" liquid out of their back ends.

"The secretions can potentially irritate your skin and has been shown to etch plastic," he said.

Can cockroaches make you sick?

Hottel, from Orkin, said cockroaches dwell in sewers, kitchen garbage bins and decaying areas, so they carry bacteria on their bodies and can contaminate food preparation areas or food itself.

"If a food inspector or health inspector came into a restaurant and saw German cockroaches, that would be deemed a safety concern," he said. "They could fall into food. That's pretty gross, right?"

They can also produce allergens which can lead to allergic reactions and asthma attacks too, Wang, from Rutgers, said.

"There are different proteins from cockroach feces (or) dead bodies," he said. "The proteins can circulate in house dust ... You may be more likely to get sensitivity or if you have asthma, you'll be more likely to have asthma attacks."

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What can you do to get rid of them?

When dealing with these pests, Wang said cockroach bait is one option.

And don't bother with foggers, liquid sprays and aerosols, he said.

"Foggers are not very effective," Wang said. "Sprays also are not effective because most cockroach populations have developed resistance to those chemicals."

He also cautions against using electronic repellants because no scientific studies have shown they actually work.

And according to Hottel, from Orkin, cleaning up can help, as well as sealing up areas where utility lines penetrate the walls of your house.

Also, make sure leaves are raked away from the house and also check your gutters.

"If you get a lot of leaf debris inside a gutter, leaves will start decaying," Hottel said. "Cockroaches can live in that."

And if you're not sure what to do or it's too much to handle on your own, don't be afraid to get your landlord involved or a pest control company.

"Especially if you're in a multi-unit housing situation because your neighbor could have them," said Hottel. "Even if you are really good at controlling (the situation) or controlling the cockroaches in your apartment, get the landlords involved to have the pest control companies check surrounding units."

Water bugs, palmetto bugs: Other names for cockroaches

What cockroaches are called depends largely on the region you live in, Hottel said.

In Maryland, people call them water bugs because they're primarily associated with sewers.

And in Florida, cockroaches are sometimes called palmetto bugs because of palm plants they live in.

Saleen Martin is a reporter on USA TODAY's NOW team. She is from Norfolk, Virginia – the 757 – and loves all things horror, witches, Christmas, and food. Follow her on Twitter at @Saleen_Martin or email her at sdmartin@usatoday.com.

This article originally appeared on USA TODAY: How to keep cockroaches out of your home: Experts say bait over sprays