TAMPA, Fla. (WFLA) — An invasive species of lizard known as Nile monitors is taking over one Florida man’s backyard.

According to NBC affiliate WBBH, Cape Coral resident Jason Derkevics spotted a six-foot-long reptile slithering around his property. Just a few moments later, he found another one, this time a baby.

“This is one of those things I’ve seen in my nightmares,” Derkevics told the local news outlet.

According to the Florida Fish and Wildlife Conservation Commission (FWC), Derkevics likely spotted a male Nile monitor which is known to be the largest lizard species in Africa. The reptiles have a reputation for growing to lengths of 6.5 feet and weighing up to 17.8 pounds.

Experts say they also engage in fierce wrestling competitions with other males for mating opportunities. Typical adults average 5 feet in length and weigh close to 15 pounds, FWC added.

The reptiles are not protected in Florida and are considered an invasive species due to their impacts on native wildlife.

“This thing, it just, it looks nasty,” said Derkevics who added that the behemoth reptile went crazy after realizing it was spotted.

(Courtesy of Florida Fish and Wildlife Conservation Commission)

“It was in a panic mode or it was in an attack mode; either one left me feeling uncomfortable,” he said.

Derkevics told the news outlet he heard about Nile monitors when he moved to Cape Coral years earlier.

“These are considered monster lizards,” said graduate student Ella Guedouar, who attends The Water School at Florida Gulf Coast University. “Cape Coral is actually the biggest population of Nile monitors in Florida,” Guedouar said.

That’s because Nile monitors are generalist feeders. FWC said they eat just about anything they can get their claws on including crabs, crayfish, mussels, snails, slugs, termites, caterpillars, beetles, spiders, grasshoppers and crickets, fish, frogs, toads, lizards, turtles, snakes, young crocodiles, and other reptiles. They can also feed on birds and their eggs, and small mammals.

Researchers believe the Florida Nile monitor population likely stem from intentional and unintentional releases from animals in captivity — and it’s at the expense of the environment.

“Due to their generalist diet, Nile monitors may impact state- and federally-listed species including sea turtles, wading birds, gopher tortoises and the American crocodile,” the FWC said.

So what should you do if you spot a Nile Monitor?

The FWC encourages people to report Nile monitor sightings. You can help by taking a picture, noting the location, and filing a report using the free IveGot1 mobile app, calling IVE-GOT1 (888-483-4681), or by reporting online at IveGot1.org.

The FWC says people should not attempt to capture Nile monitors due to their sharp teeth, strong jaws, and sharp claws.

“Although their bite would be harmless to you, it would really, really hurt,” Guedouar added.