There's a tiny pest in the nation's capital: bedbugs.

Washington overtook Baltimore as the No. 1 "Bed Bug City," based on data compiled by pest control company Orkin.

Chicago, Los Angeles and Columbus, Ohio, rounded out the top five cities on Orkin's list, which ranks metropolitan areas where Orkin performed the most bedbug treatments, residential and commercial, from December 2018 through November 2019.

Baltimore had spent three years in the top spot before falling to No. 2 this year, Orkin said.

"They are excellent hitchhikers, and they reproduce quickly which make it nearly impossible to prevent bed bugs," Orkin entomologist Chelle Hartzer said in a statement. "Sanitation has nothing to do with where you’ll find them."

While the pests can bite humans, causing itch and irritation, they are not known to transmit or spread disease, according to the Environmental Protection Agency.

The tiny insects, usually about 4 to 5 millimeters long, can spread into homes and apartments via luggage, purses and other bags. They often stay hidden and are usually nocturnal, but small black spots indicating bedbug feces or nymphs in mattress seams and other furniture could indicate their presence in a home, Orkin says.

"The key to preventing a bed bug infestation is early detection," Hartzer added.

Using a combination of chemical and non-chemical methods – including heat and cold treatments and steam cleaners – for controlling an infestation can be most effective, the EPA says. "Be aware that it will take time and patience; there is no quick fix for eradication," the agency says.

Here are the top 25 cities on Orkin's list:

1. Washington, D.C.

2. Baltimore

3. Chicago

4. Los Angeles

5. Columbus, Ohio

6. New York

7. Detroit

8. Cincinnati

9. Indianapolis

10. Atlanta

11. Cleveland, Ohio

12. Philadelphia

13. San Francisco

14. Raleigh, N.C.

15. Norfolk

16. Champaign, Ill.

17. Dallas

18. Grand Rapids

19. Pittsburgh

20. Charlotte

21. Richmond, Va.

22. Greenville, S.C.

23. Knoxville, Tenn.

24. Buffalo, N.Y.

25. Greensboro, N.C.