HOUSTON (CBSDFW.COM/AP) – One danger evacuees and first responders are dealing with along with the flooding in Houston is fire ants.

Islands of fire ants!

CBS News correspondent Omar Villafranca tweeted a photo from Houston as the ants formed a protective island in the high water.

Fire ants form a protective island as they float out the #Houston flood pic.twitter.com/UBORwAzA4R — Omar Villafranca (@OmarVillafranca) August 27, 2017

According to Orkin.com, fire ants can exist in colonies of up to 250,000 workers and will sting intruders repeatedly. Fire ants feed on animal or vegetable sources of food according to the web site.

No reports yet of anyone getting bitten by fire ants.

Tropical Storm Harvey continues to head back toward the Gulf of Mexico at a slow pace.

In its 10 p.m. CDT Sunday advisory, the National Hurricane Center reported that the storm still had sustained winds of up to 40 mph and is centered 20 miles east of Victoria, Texas, about 120 miles southwest of Houston. It continues to creep to the east-southeast at 3 mph.

That means it remains virtually stalled near the coast and continues to drop heavy rain on the Houston and Galveston areas. In the past 48 hours, numerous spots in the region have measured more than 25 inches of rainfall.

The hurricane center says Harvey’s center was expected to drift off the middle Texas coast on Monday and meander offshore through Tuesday before beginning “a slow northeastward motion.”