RICHMOND, Va. (WRIC/NEXSTAR) — While cockroaches are good for the ecosystem, they can be a nuisance and hard to avoid in some of America’s largest cities.

Pest Gnome, a company that specializes in connecting people to pest exterminators in their area, ranked the most roach-infested cities in the country.

Perhaps unsurprisingly, several highly-populated metros made the list — which was determined using data from the Census Bureau, the Bureau of Labor Statistics and the National Oceanic and Atmospheric Administration.

Houston topped the ranking, with 37% of homes showing signs of these critters in the past 12 months, according to the study. H-Town is known for its heat and humidity, and Pest Gnome said roaches thrive in these conditions.

Another Texas city came in at No. 2 on the list: San Antonio. The study found that about 28% of homes in the Alamo City showed signs of roaches in the past 12 months. Tampa, Phoenix, and Las Vegas rounded out the top five.

Here’s the full list:

1. Houston, TX
2. San Antonio, TX
3. Tampa, FL
4. Phoenix, AZ
5. Las Vegas, NV
6. Miami, FL
7. Atlanta, GA
8. Birmingham, AL
9. Dallas, TX
10. Oklahoma City, OK
11. New York, NY
12. Richmond, VA
13. Los Angeles, CA
14. Washington, D.C.
15. Philadelphia, PA
16. Baltimore, MD
17. Riverside, CA
18. Chicago, IL
19. Minneapolis, MN
20. San Jose, CA
21. Boston, MA
22. Detroit, MI
23. San Francisco, CA
24. Rochester, NY
25. Seattle, WA

Cockroaches play an important role in our ecosystem since they are a food source for other creatures, like toads, mice, beetles and spiders, according to Orkin.

But they can also pose a health risk to humans.

“Cockroaches are known to transfer disease pathogens, such as the various bacteria that produce ‘food poisoning’ in humans, by contaminating food, food preparation surfaces, dishes and eating utensils,” the Illinois Department of Public Health stated on its website.

To prevent roaches from roaming in your home, Pest Gnome recommends sealing any points of entry, cleaning up any stray crumbs, fixing leaky pipes and using Raid and roach motels. If all else fails, call an exterminator.