PHILADELPHIA (WPVI) -- Philadelphia is falling in the ranks of a notorious list dealing with bed bugs.
The city is now number 12 on Orkin's list of the worst cities for Bed Bugs.
That is down 2 spots from number 10.
Last year, Terminex ranked Philadelphia as having the worst bed bug problem in the country
The list is based on treatment data between December 2018 and November 30 of last year.
Washington DC holds the top spot, beating out Baltimore, which spent 3 years topping the list.
The ranking includes both residential and commercial treatments.
The 2020 ranking for cities dealing with bed bugs is as follows:
Washington, D.C. (+1)
Baltimore (-1)
Chicago
Los Angeles
Columbus, OH
New York
Detroit (+1)
Cincinnati (-1)
Indianapolis (+5)
Atlanta (-1)
Cleveland, OH
Philadelphia (-2)
San Francisco (-1)
Raleigh, NC (-1)
Norfolk (+2)
Champaign, IL (+7)
Dallas (-2)
Grand Rapids (+2)
Pittsburgh (+6)
Charlotte (-1)
Richmond, VA (-5)
Greenville, SC (-4)
Knoxville, TN (-1)
Buffalo, NY (-3)
Greensboro, NC (-4)
Charleston, WV (+5)
Denver
St. Louis (+2)
Nashville (-5)
Lansing (+2)
Flint (+16)
Miami (-3)
Milwaukee (-3)
Tampa (+1)
Omaha (+2)
Orlando (+5)
Davenport, IA (+5)
Houston (-12)
Syracuse (-6)
Boston (-2)
Cedar Rapids, IA (+3)
Myrtle Beach (new to list)
Seattle (-4)
San Diego (+5)
Phoenix (-11)
Fort Wayne, IN (+2)
Las Vegas (-7)
Hartford, CT (-5)
Dayton, OH (-3)
Toledo, OH (new to list)
"While bed bugs have not been found to transmit any diseases to humans, they can be an elusive threat to households," said Chelle Hartzer, an Orkin entomologist. "They are excellent hitchhikers, and they reproduce quickly which make it nearly impossible to prevent bed bugs. Sanitation has nothing to do with where you'll find them."
RELATED: Suspect sought after releasing bedbugs in Pennsylvania Walmart
Bed bugs, which are typically 4-5 mm in length and red to dark brown in color, can travel from place to place with ease, including luggage, purses and other belongings. Normally nocturnal, bed bugs will come out of hiding to take blood meals from sleeping or quietly resting humans.
According to the 2018 "Bugs without Borders Survey" by the National Pest Management Association (NPMA), the top three places where pest professionals report finding bed bugs are single-family homes (91 percent), apartments/condominiums (89 percent) and hotels/motels (68 percent). With that, hotels spend an average of $6,383 per bed bug incident.
Bed bugs are known for rapid population growth. Females can deposit one to five eggs a day and may lay 200 to 500 eggs in their lifetime. Under normal room temperatures and with an adequate food supply, they can live for more than 300 days, often making treatment challenging.
"The key to preventing a bed bug infestation is early detection," Hartzer said. "When one or more bed bugs enter a space, we call it an introduction. During an introduction, bed bugs probably haven't started reproducing yet, but they could soon. Vigilance is key to stopping bed bugs before infestation levels."
Tell-tale signs of a bed bug introduction could include small black spots indicating bed bug feces or nymph bed bugs in places such as mattress seams, bed frames and furniture. Their small size and ability to hide make them difficult to see during the day, so it's important to look for the black, ink-like stains they can leave behind.